diff --git a/.gitignore b/.gitignore
index 569e6ce20b..10a4e85c2e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -19,6 +19,10 @@
 !/phpBB/styles/all
 node_modules
 /phpBB/vendor
+/phpBB/vendor-ext/*
+!/phpBB/vendor-ext/.git-keep
+/phpBB/composer-ext.json
+/phpBB/composer-ext.lock
 /tests/phpbb_unit_tests.sqlite*
 /tests/test_config*.php
 /tests/tmp/*
diff --git a/build/build.xml b/build/build.xml
index f93ff0079b..34e1d5f930 100644
--- a/build/build.xml
+++ b/build/build.xml
@@ -95,6 +95,7 @@
 				--ignore=${project.basedir}/phpBB/install/database_update.php
 				--ignore=${project.basedir}/phpBB/phpbb/*
 				--ignore=${project.basedir}/phpBB/vendor/*
+				--ignore=${project.basedir}/phpBB/vendor-ext/*
 				phpBB"
 			dir="." returnProperty="retval-php-legacy" passthru="true" />
 		<exec command="phpBB/vendor/bin/phpcs
diff --git a/phpBB/adm/style/acp_ext_catalog.html b/phpBB/adm/style/acp_ext_catalog.html
new file mode 100644
index 0000000000..1be94258e8
--- /dev/null
+++ b/phpBB/adm/style/acp_ext_catalog.html
@@ -0,0 +1,130 @@
+{% include('overall_header.html') %}
+
+<a id="maincontent"></a>
+
+<h1>{{ lang( 'EXTENSIONS_CATALOG') }}</h1>
+
+<p>{{ lang( 'EXTENSIONS_CATALOG_EXPLAIN') }}</p>
+
+<fieldset class="quick quick-left">
+	<span class="small"><a href="https://www.phpbb.com/go/customise/extensions/{{ PHPBB_MAJOR }}" target="_blank">{{ lang('BROWSE_EXTENSIONS_DATABASE') }}</a> &bull; <a href="javascript:phpbb.toggleDisplay('catalog_settings');">{{ lang('SETTINGS') }}</a></span>
+</fieldset>
+
+{% if pagination is defined %}
+	<div class="pagination top-pagination">
+		{% include('pagination.html') %}
+	</div>
+{% endif %}
+
+<form id="catalog_settings" method="post" action="{{ U_ACTION }}" style="display:none">
+	<fieldset style="clear: both;">
+		<legend>{{ lang('EXTENSIONS_CATALOG_SETTINGS') }}</legend>
+		<dl>
+			<dt><label for="enable_on_install">{{ lang('ENABLE_ON_INSTALL') }}{{ lang('COLON') }}</label></dt>
+			<dd>
+				<label><input type="radio" id="enable_on_install" name="enable_on_install" class="radio" value="1"{% if settings.enable_on_install %} checked="checked" {% endif %} /> {{ lang('YES') }}</label>
+				<label><input type="radio" name="enable_on_install" class="radio" value="0"{% if not settings.enable_on_install %} checked="checked" {% endif %} /> {{ lang('NO') }}</label>
+			</dd>
+		</dl>
+		<dl>
+			<dt><label for="purge_on_remove">{{ lang('PURGE_ON_REMOVE') }}{{ lang('COLON') }}</label></dt>
+			<dd>
+				<label><input type="radio" id="purge_on_remove" name="purge_on_remove" class="radio" value="1"{% if settings.purge_on_remove %} checked="checked" {% endif %} /> {{ lang('YES') }}</label>
+				<label><input type="radio" name="purge_on_remove" class="radio" value="0"{% if not settings.purge_on_remove %} checked="checked" {% endif %} /> {{ lang('NO') }}</label>
+			</dd>
+		</dl>
+		<dl>
+			<dt>
+				<label for="repositories">{{ lang('COMPOSER_REPOSITORIES') }}{{ lang('COLON') }}</label><br />
+				<span class="explain">
+					{{ lang('COMPOSER_REPOSITORIES_EXPLAIN') }}
+				</span>
+			</dt>
+			<dd>
+				<textarea id="repositories" name="repositories" rows="5" cols="30">{{ settings.repositories|join('\n') }}</textarea>
+			</dd>
+		</dl>
+		<dl>
+			<dt>
+				<label for="enable_packagist">{{ lang('ENABLE_PACKAGIST') }}{{ lang('COLON') }}</label><br />
+				<span class="explain">
+					<strong class="error">{{ lang('WARNING') }}{{ lang('COLON') }}</strong> {{ lang('ENABLE_PACKAGIST_EXPLAIN') }}
+				</span>
+			</dt>
+			<dd>
+				<label><input type="radio" id="enable_packagist" name="enable_packagist" class="radio" value="1"{% if settings.enable_packagist %} checked="checked" {% endif %} /> {{ lang('YES') }}</label>
+				<label><input type="radio" name="enable_packagist" class="radio" value="0"{% if not settings.enable_packagist %} checked="checked" {% endif %} /> {{ lang('NO') }}</label>
+			</dd>
+		</dl>
+		<dl>
+			<dt>
+				<label for="minimum_stability">{{ lang('COMPOSER_MINIMUM_STABILITY') }}{{ lang('COLON') }}</label><br />
+				<span class="explain">
+					<strong class="error">{{ lang('WARNING') }}{{ lang('COLON') }}</strong> {{ lang('COMPOSER_MINIMUM_STABILITY_EXPLAIN') }}
+				</span>
+			</dt>
+			<dd>
+				<select id="minimum_stability" name="minimum_stability">
+					{% for stability in settings.stabilities %}
+						<option value="{{ stability }}"{% if stability === settings.minimum_stability %} selected='selected'{% endif %}>{{ lang('STABILITY_' ~ stability|upper) }}</option>
+					{% endfor %}
+				</select>
+			</dd>
+		</dl>
+
+		<p class="submit-buttons">
+			<input class="button1" type="submit" name="update" value="{{ lang('SUBMIT') }}" />&nbsp;
+			<input class="button2" type="reset" name="reset" value="{{ lang('RESET') }}" />
+			<input type="hidden" name="action" value="set_catalog_settings" />
+			{{ S_FORM_TOKEN }}
+		</p>
+	</fieldset>
+</form>
+
+{% if extensions is empty %}
+<tr>
+	<td colspan="4"><div class="errorbox notice">{{ lang('NO_EXTENSION_AVAILABLE') }}</div></td>
+</tr>
+{% else %}
+<table class="table1">
+	<col class="row1" ><col class="row1" ><col class="row1" ><col class="row2" >
+<thead>
+	<tr>
+		<th style="width: 25%;">{{ lang("EXTENSION_NAME") }}</th>
+		<th style="text-align: center; width: 10%;">{{ lang("VERSION") }}</th>
+		<th>{{ lang("DESCRIPTION") }}</th>
+		<th style="text-align: center; width: 15%;">{{ lang("EXTENSION_ACTIONS") }}</th>
+	</tr>
+</thead>
+<tbody>
+{% for extension in extensions %}
+	<tr>
+		<td>
+			<strong>{{ extension.display_name }}</strong><br />
+			{{ extension.name }}
+		</td>
+		<td style="text-align: center">{{ extension.version }}</td>
+		<td>{{ extension.description }} &bull; <a href="{{ extension.url }}">{{ lang('HOMEPAGE') }}</a></td>
+		<td style="text-align: center">
+			{% if extension.name in managed_extensions %}
+				<span style="color: #228822;">{{ lang('INSTALLED') }}</span>
+			{% elseif extension.name in installed_extensions -%}
+				<span style="color: #BC2A4D;">{{ lang('INSTALLED_MANUALLY') }}</span>
+				(<a href="{{ U_ACTION }}&amp;action=manage&amp;extension={{ extension.composer_name|url_encode }}">{{ lang('MANAGE') }}</a>)
+			{% elseif not enabled -%}
+				<a href="{{ U_ACTION }}&amp;action=install&amp;extension={{ extension.composer_name|url_encode }}">{{ lang('INSTALL') }}</a>
+			{%- endif -%}
+		</td>
+	</tr>
+{% endfor %}
+</tbody>
+</table>
+{% endif %}
+
+{% if pagination is defined %}
+	<div class="pagination bottom-pagination">
+		{% include('pagination.html') %}
+	</div>
+{% endif %}
+
+{% include('overall_footer.html') %}
diff --git a/phpBB/adm/style/acp_ext_list.html b/phpBB/adm/style/acp_ext_list.html
index af9e00a614..797cdc09bd 100644
--- a/phpBB/adm/style/acp_ext_list.html
+++ b/phpBB/adm/style/acp_ext_list.html
@@ -7,7 +7,7 @@
 	<p>{L_EXTENSIONS_EXPLAIN}</p>
 
 	<fieldset class="quick">
-		<span class="small"><a href="https://www.phpbb.com/go/customise/extensions/3.1" target="_blank">{L_BROWSE_EXTENSIONS_DATABASE}</a> &bull; <a href="{U_VERSIONCHECK_FORCE}">{L_VERSIONCHECK_FORCE_UPDATE_ALL}</a> &bull; <a href="javascript:phpbb.toggleDisplay('version_check_settings');">{L_SETTINGS}</a></span>
+		<span class="small"><a href="{U_VERSIONCHECK_FORCE}">{L_VERSIONCHECK_FORCE_UPDATE_ALL}</a> &bull; <a href="javascript:phpbb.toggleDisplay('version_check_settings');">{L_SETTINGS}</a></span>
 	</fieldset>
 
 	<form id="version_check_settings" method="post" action="{U_ACTION}" style="display:none">
@@ -59,7 +59,7 @@
 			<td style="text-align: center;"><a href="{enabled.U_DETAILS}">{L_DETAILS}</a></td>
 			<td style="text-align: center;">
 				<!-- BEGIN actions -->
-					<a href="{enabled.actions.U_ACTION}"<!-- IF enabled.actions.L_ACTION_EXPLAIN --> title="{enabled.actions.L_ACTION_EXPLAIN}"<!-- ENDIF -->>{enabled.actions.L_ACTION}</a>
+					<a href="{enabled.actions.U_ACTION}"<!-- IF enabled.actions.L_ACTION_EXPLAIN --> title="{enabled.actions.L_ACTION_EXPLAIN}"<!-- ENDIF --><!-- IF enabled.actions.COLOR -->  style="color: {enabled.actions.COLOR};"<!-- ENDIF -->>{enabled.actions.L_ACTION}</a>
 					<!-- IF not enabled.actions.S_LAST_ROW -->&nbsp;|&nbsp;<!-- ENDIF -->
 				<!-- END actions -->
 			</td>
@@ -86,7 +86,7 @@
 			</td>
 			<td style="text-align: center;">
 				<!-- BEGIN actions -->
-					<a href="{disabled.actions.U_ACTION}"<!-- IF disabled.actions.L_ACTION_EXPLAIN --> title="{disabled.actions.L_ACTION_EXPLAIN}"<!-- ENDIF -->>{disabled.actions.L_ACTION}</a>
+					<a href="{disabled.actions.U_ACTION}"<!-- IF disabled.actions.L_ACTION_EXPLAIN --> title="{disabled.actions.L_ACTION_EXPLAIN}"<!-- ENDIF --><!-- IF disabled.actions.COLOR -->  style="color: {disabled.actions.COLOR};"<!-- ENDIF -->>{disabled.actions.L_ACTION}</a>
 					<!-- IF not disabled.actions.S_LAST_ROW -->&nbsp;|&nbsp;<!-- ENDIF -->
 				<!-- END actions -->
 			</td>
diff --git a/phpBB/adm/style/admin.css b/phpBB/adm/style/admin.css
index f81dd35531..6e736ee6d2 100644
--- a/phpBB/adm/style/admin.css
+++ b/phpBB/adm/style/admin.css
@@ -1333,6 +1333,18 @@ p.quick {
 	text-align: left;
 }
 
+fieldset.quick-left,
+p.quick-left {
+	float: left;
+	margin: 15px 0 5px;
+	padding: 0;
+}
+
+.rtl fieldset.quick-left,
+.rtl p.quick-left {
+	float: right;
+}
+
 fieldset.quick legend {
 	display: none;
 }
@@ -2959,3 +2971,10 @@ fieldset.permissions .permissions-switch {
 /* stylelint-enable selector-no-qualifying-type */
 /* stylelint-enable declaration-property-unit-blacklist */
 /* stylelint-enable declaration-property-unit-whitelist */
+
+.console-output {
+	font-family: monospace;
+	background-color: #2a2a2a;
+	color: #f1f1f1;
+	overflow-x: scroll;
+}
diff --git a/phpBB/adm/style/detailed_message_body.html b/phpBB/adm/style/detailed_message_body.html
new file mode 100644
index 0000000000..bc904d7eb6
--- /dev/null
+++ b/phpBB/adm/style/detailed_message_body.html
@@ -0,0 +1,14 @@
+<!-- INCLUDE overall_header.html -->
+
+<div {% if S_USER_NOTICE %}class="successbox"{% else %}class="errorbox"{% endif %}>
+	<h3>{{ MESSAGE_TITLE }}</h3>
+	<p>{{ MESSAGE_TEXT }}</p>
+</div>
+
+<div>
+	<fieldset class="console-output">
+		<pre>{{ MESSAGE_DETAIL }}</pre>
+	</fieldset>
+</div>
+
+<!-- INCLUDE overall_footer.html -->
diff --git a/phpBB/bin/phpbbcli.php b/phpBB/bin/phpbbcli.php
index 6bd217ec07..d007ab3914 100755
--- a/phpBB/bin/phpbbcli.php
+++ b/phpBB/bin/phpbbcli.php
@@ -71,6 +71,11 @@ require($phpbb_root_path . 'includes/compatibility_globals.' . $phpEx);
 
 register_compatibility_globals();
 
+if (@is_file($phpbb_root_path . $config['exts_composer_vendor_dir'] . '/autoload.php'))
+{
+	require_once($phpbb_root_path . $config['exts_composer_vendor_dir'] . '/autoload.php');
+}
+
 /** @var \phpbb\language\language $language */
 $language = $phpbb_container->get('language');
 $language->add_lang(array('common', 'acp/common', 'cli'));
diff --git a/phpBB/common.php b/phpBB/common.php
index 70feb55d04..ea386978fb 100644
--- a/phpBB/common.php
+++ b/phpBB/common.php
@@ -141,6 +141,11 @@ require($phpbb_root_path . 'includes/compatibility_globals.' . $phpEx);
 
 register_compatibility_globals();
 
+if (@is_file($phpbb_root_path . $config['exts_composer_vendor_dir'] . '/autoload.php'))
+{
+	require_once($phpbb_root_path . $config['exts_composer_vendor_dir'] . '/autoload.php');
+}
+
 // Add own hook handler
 require($phpbb_root_path . 'includes/hooks/index.' . $phpEx);
 $phpbb_hook = new phpbb_hook(array('exit_handler', 'phpbb_user_session_handler', 'append_sid', array('template', 'display')));
diff --git a/phpBB/composer-ext.json b/phpBB/composer-ext.json
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/phpBB/composer-ext.lock b/phpBB/composer-ext.lock
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/phpBB/composer.json b/phpBB/composer.json
index 2207d10b9d..6f8e930c8b 100644
--- a/phpBB/composer.json
+++ b/phpBB/composer.json
@@ -27,6 +27,7 @@
 	"require": {
 		"php": ">=5.5.9",
 		"bantu/ini-get-wrapper": "1.0.*",
+		"composer/composer": "^1.0",
 		"google/recaptcha": "~1.1",
 		"guzzlehttp/guzzle": "~6.2",
 		"lusitanian/oauth": "^0.8.1",
diff --git a/phpBB/composer.lock b/phpBB/composer.lock
index 0d258bc677..4fff2b628a 100644
--- a/phpBB/composer.lock
+++ b/phpBB/composer.lock
@@ -4,8 +4,8 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#composer-lock-the-lock-file",
         "This file is @generated automatically"
     ],
-    "hash": "c53f2fa544168309d695bb1855c98c24",
-    "content-hash": "4bc93e90a4852f936c13986c3823831b",
+    "hash": "fb27e08d4d657b78f87a3327a41d9e20",
+    "content-hash": "274c9cfc16d9a9cd40daffe7383d568a",
     "packages": [
         {
             "name": "bantu/ini-get-wrapper",
@@ -37,6 +37,263 @@
             "description": "Convenience wrapper around ini_get()",
             "time": "2014-09-15 13:12:35"
         },
+        {
+            "name": "composer/ca-bundle",
+            "version": "1.0.3",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/composer/ca-bundle.git",
+                "reference": "5df9ed0ed0c9506ea6404a23450854e5df15cc12"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/composer/ca-bundle/zipball/5df9ed0ed0c9506ea6404a23450854e5df15cc12",
+                "reference": "5df9ed0ed0c9506ea6404a23450854e5df15cc12",
+                "shasum": ""
+            },
+            "require": {
+                "ext-openssl": "*",
+                "ext-pcre": "*",
+                "php": "^5.3.2 || ^7.0"
+            },
+            "require-dev": {
+                "symfony/process": "^2.5 || ^3.0"
+            },
+            "suggest": {
+                "symfony/process": "This is necessary to reliably check whether openssl_x509_parse is vulnerable on older php versions, but can be ignored on PHP 5.5.6+"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "1.x-dev"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "Composer\\CaBundle\\": "src"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Jordi Boggiano",
+                    "email": "j.boggiano@seld.be",
+                    "homepage": "http://seld.be"
+                }
+            ],
+            "description": "Lets you find a path to the system CA bundle, and includes a fallback to the Mozilla CA bundle.",
+            "keywords": [
+                "cabundle",
+                "cacert",
+                "certificate",
+                "ssl",
+                "tls"
+            ],
+            "time": "2016-07-18 23:07:53"
+        },
+        {
+            "name": "composer/composer",
+            "version": "1.3.3",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/composer/composer.git",
+                "reference": "989d68725bc8ebf97e795d4feb386f52adb096e3"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/composer/composer/zipball/989d68725bc8ebf97e795d4feb386f52adb096e3",
+                "reference": "989d68725bc8ebf97e795d4feb386f52adb096e3",
+                "shasum": ""
+            },
+            "require": {
+                "composer/ca-bundle": "^1.0",
+                "composer/semver": "^1.0",
+                "composer/spdx-licenses": "^1.0",
+                "justinrainbow/json-schema": "^1.6 || ^2.0 || ^3.0 || ^4.0",
+                "php": "^5.3.2 || ^7.0",
+                "psr/log": "^1.0",
+                "seld/cli-prompt": "^1.0",
+                "seld/jsonlint": "^1.4",
+                "seld/phar-utils": "^1.0",
+                "symfony/console": "^2.7 || ^3.0",
+                "symfony/filesystem": "^2.7 || ^3.0",
+                "symfony/finder": "^2.7 || ^3.0",
+                "symfony/process": "^2.7 || ^3.0"
+            },
+            "require-dev": {
+                "phpunit/phpunit": "^4.5 || ^5.0.5",
+                "phpunit/phpunit-mock-objects": "^2.3 || ^3.0"
+            },
+            "suggest": {
+                "ext-openssl": "Enabling the openssl extension allows you to access https URLs for repositories and packages",
+                "ext-zip": "Enabling the zip extension allows you to unzip archives",
+                "ext-zlib": "Allow gzip compression of HTTP requests"
+            },
+            "bin": [
+                "bin/composer"
+            ],
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "1.3-dev"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "Composer\\": "src/Composer"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Nils Adermann",
+                    "email": "naderman@naderman.de",
+                    "homepage": "http://www.naderman.de"
+                },
+                {
+                    "name": "Jordi Boggiano",
+                    "email": "j.boggiano@seld.be",
+                    "homepage": "http://seld.be"
+                }
+            ],
+            "description": "Composer helps you declare, manage and install dependencies of PHP projects, ensuring you have the right stack everywhere.",
+            "homepage": "https://getcomposer.org/",
+            "keywords": [
+                "autoload",
+                "dependency",
+                "package"
+            ],
+            "time": "2017-03-08 10:06:43"
+        },
+        {
+            "name": "composer/semver",
+            "version": "1.4.2",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/composer/semver.git",
+                "reference": "c7cb9a2095a074d131b65a8a0cd294479d785573"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/composer/semver/zipball/c7cb9a2095a074d131b65a8a0cd294479d785573",
+                "reference": "c7cb9a2095a074d131b65a8a0cd294479d785573",
+                "shasum": ""
+            },
+            "require": {
+                "php": "^5.3.2 || ^7.0"
+            },
+            "require-dev": {
+                "phpunit/phpunit": "^4.5 || ^5.0.5",
+                "phpunit/phpunit-mock-objects": "2.3.0 || ^3.0"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "1.x-dev"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "Composer\\Semver\\": "src"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Nils Adermann",
+                    "email": "naderman@naderman.de",
+                    "homepage": "http://www.naderman.de"
+                },
+                {
+                    "name": "Jordi Boggiano",
+                    "email": "j.boggiano@seld.be",
+                    "homepage": "http://seld.be"
+                },
+                {
+                    "name": "Rob Bast",
+                    "email": "rob.bast@gmail.com",
+                    "homepage": "http://robbast.nl"
+                }
+            ],
+            "description": "Semver library that offers utilities, version constraint parsing and validation.",
+            "keywords": [
+                "semantic",
+                "semver",
+                "validation",
+                "versioning"
+            ],
+            "time": "2016-08-30 16:08:34"
+        },
+        {
+            "name": "composer/spdx-licenses",
+            "version": "1.1.4",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/composer/spdx-licenses.git",
+                "reference": "88c26372b1afac36d8db601cdf04ad8716f53d88"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/composer/spdx-licenses/zipball/88c26372b1afac36d8db601cdf04ad8716f53d88",
+                "reference": "88c26372b1afac36d8db601cdf04ad8716f53d88",
+                "shasum": ""
+            },
+            "require": {
+                "php": "^5.3.2 || ^7.0"
+            },
+            "require-dev": {
+                "phpunit/phpunit": "^4.5 || ^5.0.5",
+                "phpunit/phpunit-mock-objects": "2.3.0 || ^3.0"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "1.x-dev"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "Composer\\Spdx\\": "src"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Nils Adermann",
+                    "email": "naderman@naderman.de",
+                    "homepage": "http://www.naderman.de"
+                },
+                {
+                    "name": "Jordi Boggiano",
+                    "email": "j.boggiano@seld.be",
+                    "homepage": "http://seld.be"
+                },
+                {
+                    "name": "Rob Bast",
+                    "email": "rob.bast@gmail.com",
+                    "homepage": "http://robbast.nl"
+                }
+            ],
+            "description": "SPDX licenses list and validation library.",
+            "keywords": [
+                "license",
+                "spdx",
+                "validator"
+            ],
+            "time": "2016-05-04 12:27:30"
+        },
         {
             "name": "google/recaptcha",
             "version": "1.1.2",
@@ -253,6 +510,72 @@
             ],
             "time": "2016-06-24 23:00:38"
         },
+        {
+            "name": "justinrainbow/json-schema",
+            "version": "2.0.5",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/justinrainbow/json-schema.git",
+                "reference": "6b2a33e6a768f96bdc2ead5600af0822eed17d67"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/justinrainbow/json-schema/zipball/6b2a33e6a768f96bdc2ead5600af0822eed17d67",
+                "reference": "6b2a33e6a768f96bdc2ead5600af0822eed17d67",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.3.3"
+            },
+            "require-dev": {
+                "json-schema/json-schema-test-suite": "1.2.0",
+                "phpdocumentor/phpdocumentor": "~2",
+                "phpunit/phpunit": "^4.8.22"
+            },
+            "bin": [
+                "bin/validate-json"
+            ],
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "2.0.x-dev"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "JsonSchema\\": "src/JsonSchema/"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Bruno Prieto Reis",
+                    "email": "bruno.p.reis@gmail.com"
+                },
+                {
+                    "name": "Justin Rainbow",
+                    "email": "justin.rainbow@gmail.com"
+                },
+                {
+                    "name": "Igor Wiedler",
+                    "email": "igor@wiedler.ch"
+                },
+                {
+                    "name": "Robert Schönthal",
+                    "email": "seroscho@googlemail.com"
+                }
+            ],
+            "description": "A library to validate a json schema.",
+            "homepage": "https://github.com/justinrainbow/json-schema",
+            "keywords": [
+                "json",
+                "schema"
+            ],
+            "time": "2016-06-02 10:59:52"
+        },
         {
             "name": "lusitanian/oauth",
             "version": "v0.8.10",
@@ -703,6 +1026,144 @@
             ],
             "time": "2017-01-22 17:12:21"
         },
+        {
+            "name": "seld/cli-prompt",
+            "version": "1.0.2",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/Seldaek/cli-prompt.git",
+                "reference": "8cbe10923cae5bcd7c5a713f6703fc4727c8c1b4"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/Seldaek/cli-prompt/zipball/8cbe10923cae5bcd7c5a713f6703fc4727c8c1b4",
+                "reference": "8cbe10923cae5bcd7c5a713f6703fc4727c8c1b4",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.3"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "1.x-dev"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "Seld\\CliPrompt\\": "src/"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Jordi Boggiano",
+                    "email": "j.boggiano@seld.be"
+                }
+            ],
+            "description": "Allows you to prompt for user input on the command line, and optionally hide the characters they type",
+            "keywords": [
+                "cli",
+                "console",
+                "hidden",
+                "input",
+                "prompt"
+            ],
+            "time": "2016-04-18 09:31:41"
+        },
+        {
+            "name": "seld/jsonlint",
+            "version": "1.4.0",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/Seldaek/jsonlint.git",
+                "reference": "66834d3e3566bb5798db7294619388786ae99394"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/Seldaek/jsonlint/zipball/66834d3e3566bb5798db7294619388786ae99394",
+                "reference": "66834d3e3566bb5798db7294619388786ae99394",
+                "shasum": ""
+            },
+            "require": {
+                "php": "^5.3 || ^7.0"
+            },
+            "bin": [
+                "bin/jsonlint"
+            ],
+            "type": "library",
+            "autoload": {
+                "psr-4": {
+                    "Seld\\JsonLint\\": "src/Seld/JsonLint/"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Jordi Boggiano",
+                    "email": "j.boggiano@seld.be",
+                    "homepage": "http://seld.be"
+                }
+            ],
+            "description": "JSON Linter",
+            "keywords": [
+                "json",
+                "linter",
+                "parser",
+                "validator"
+            ],
+            "time": "2015-11-21 02:21:41"
+        },
+        {
+            "name": "seld/phar-utils",
+            "version": "1.0.1",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/Seldaek/phar-utils.git",
+                "reference": "7009b5139491975ef6486545a39f3e6dad5ac30a"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/Seldaek/phar-utils/zipball/7009b5139491975ef6486545a39f3e6dad5ac30a",
+                "reference": "7009b5139491975ef6486545a39f3e6dad5ac30a",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.3"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "1.x-dev"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "Seld\\PharUtils\\": "src/"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Jordi Boggiano",
+                    "email": "j.boggiano@seld.be"
+                }
+            ],
+            "description": "PHAR file format utilities, for when PHP phars you up",
+            "keywords": [
+                "phra"
+            ],
+            "time": "2015-10-13 18:44:15"
+        },
         {
             "name": "symfony/config",
             "version": "v3.2.0",
@@ -1294,6 +1755,55 @@
             ],
             "time": "2016-11-14 01:06:16"
         },
+        {
+            "name": "symfony/process",
+            "version": "v3.1.3",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/symfony/process.git",
+                "reference": "04c2dfaae4ec56a5c677b0c69fac34637d815758"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/symfony/process/zipball/04c2dfaae4ec56a5c677b0c69fac34637d815758",
+                "reference": "04c2dfaae4ec56a5c677b0c69fac34637d815758",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.5.9"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "3.1-dev"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "Symfony\\Component\\Process\\": ""
+                },
+                "exclude-from-classmap": [
+                    "/Tests/"
+                ]
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Fabien Potencier",
+                    "email": "fabien@symfony.com"
+                },
+                {
+                    "name": "Symfony Community",
+                    "homepage": "https://symfony.com/contributors"
+                }
+            ],
+            "description": "Symfony Process Component",
+            "homepage": "https://symfony.com",
+            "time": "2016-07-28 11:13:48"
+        },
         {
             "name": "symfony/proxy-manager-bridge",
             "version": "v3.2.0",
@@ -3231,55 +3741,6 @@
             "homepage": "https://symfony.com",
             "time": "2016-11-25 12:32:42"
         },
-        {
-            "name": "symfony/process",
-            "version": "v3.2.0",
-            "source": {
-                "type": "git",
-                "url": "https://github.com/symfony/process.git",
-                "reference": "02ea84847aad71be7e32056408bb19f3a616cdd3"
-            },
-            "dist": {
-                "type": "zip",
-                "url": "https://api.github.com/repos/symfony/process/zipball/02ea84847aad71be7e32056408bb19f3a616cdd3",
-                "reference": "02ea84847aad71be7e32056408bb19f3a616cdd3",
-                "shasum": ""
-            },
-            "require": {
-                "php": ">=5.5.9"
-            },
-            "type": "library",
-            "extra": {
-                "branch-alias": {
-                    "dev-master": "3.2-dev"
-                }
-            },
-            "autoload": {
-                "psr-4": {
-                    "Symfony\\Component\\Process\\": ""
-                },
-                "exclude-from-classmap": [
-                    "/Tests/"
-                ]
-            },
-            "notification-url": "https://packagist.org/downloads/",
-            "license": [
-                "MIT"
-            ],
-            "authors": [
-                {
-                    "name": "Fabien Potencier",
-                    "email": "fabien@symfony.com"
-                },
-                {
-                    "name": "Symfony Community",
-                    "homepage": "https://symfony.com/contributors"
-                }
-            ],
-            "description": "Symfony Process Component",
-            "homepage": "https://symfony.com",
-            "time": "2016-11-24 10:40:28"
-        },
         {
             "name": "webmozart/assert",
             "version": "1.2.0",
diff --git a/phpBB/config/default/container/services.yml b/phpBB/config/default/container/services.yml
index 9bb1d673f4..17fa223dda 100644
--- a/phpBB/config/default/container/services.yml
+++ b/phpBB/config/default/container/services.yml
@@ -8,6 +8,7 @@ imports:
     - { resource: services_cron.yml }
     - { resource: services_db.yml }
     - { resource: services_event.yml }
+    - { resource: services_extensions.yml }
     - { resource: services_feed.yml }
     - { resource: services_files.yml }
     - { resource: services_filesystem.yml }
@@ -98,18 +99,6 @@ services:
             - '%core.root_path%'
             - '@template'
 
-    ext.manager:
-        class: phpbb\extension\manager
-        arguments:
-            - '@service_container'
-            - '@dbal.conn'
-            - '@config'
-            - '@filesystem'
-            - '%tables.ext%'
-            - '%core.root_path%'
-            - '%core.php_ext%'
-            - '@cache'
-
     file_downloader:
         class: phpbb\file_downloader
 
diff --git a/phpBB/config/default/container/services_console.yml b/phpBB/config/default/container/services_console.yml
index e25ab4f03f..94c7c61812 100644
--- a/phpBB/config/default/container/services_console.yml
+++ b/phpBB/config/default/container/services_console.yml
@@ -141,6 +141,33 @@ services:
         tags:
             - { name: console.command }
 
+    console.command.extension.install:
+        class: phpbb\console\command\extension\install
+        arguments:
+            - '@user'
+            - '@ext.composer.manager'
+            - '@language'
+        tags:
+            - { name: console.command }
+
+    console.command.extension.list_available:
+        class: phpbb\console\command\extension\list_available
+        arguments:
+            - '@user'
+            - '@ext.composer.manager'
+            - '@language'
+        tags:
+            - { name: console.command }
+
+    console.command.extension.manage:
+        class: phpbb\console\command\extension\manage
+        arguments:
+            - '@user'
+            - '@ext.composer.manager'
+            - '@language'
+        tags:
+            - { name: console.command }
+
     console.command.extension.purge:
         class: phpbb\console\command\extension\purge
         arguments:
@@ -150,6 +177,15 @@ services:
         tags:
             - { name: console.command }
 
+    console.command.extension.remove:
+        class: phpbb\console\command\extension\remove
+        arguments:
+            - '@user'
+            - '@ext.composer.manager'
+            - '@language'
+        tags:
+            - { name: console.command }
+
     console.command.extension.show:
         class: phpbb\console\command\extension\show
         arguments:
@@ -159,6 +195,15 @@ services:
         tags:
             - { name: console.command }
 
+    console.command.extension.update:
+        class: phpbb\console\command\extension\update
+        arguments:
+            - '@user'
+            - '@ext.composer.manager'
+            - '@language'
+        tags:
+            - { name: console.command }
+
     console.command.fixup.recalculate_email_hash:
         class: phpbb\console\command\fixup\recalculate_email_hash
         arguments:
diff --git a/phpBB/config/default/container/services_extensions.yml b/phpBB/config/default/container/services_extensions.yml
new file mode 100644
index 0000000000..e07ec1fd09
--- /dev/null
+++ b/phpBB/config/default/container/services_extensions.yml
@@ -0,0 +1,48 @@
+services:
+    ext.manager:
+        class: phpbb\extension\manager
+        arguments:
+            - '@service_container'
+            - '@dbal.conn'
+            - '@config'
+            - '@filesystem'
+            - '%tables.ext%'
+            - '%core.root_path%'
+            - '%core.php_ext%'
+            - '@cache'
+
+    ext.composer.installer:
+        class: phpbb\composer\installer
+        arguments:
+            - '%core.root_path%'
+            - '@filesystem'
+            - '@request'
+            - '@config'
+
+    ext.composer.manager:
+        class: phpbb\composer\extension_manager
+        arguments:
+            - '@ext.composer.installer'
+            - '@cache.driver'
+            - '@ext.manager'
+            - '@filesystem'
+            - phpbb-extension
+            - EXTENSIONS_
+            - '%core.root_path%'
+            - '@config'
+
+    style.composer.manager:
+        class: phpbb\composer\manager
+        arguments:
+            - '@ext.composer.installer'
+            - '@cache.driver'
+            - phpbb-style
+            - STYLES_
+
+    lang.composer.manager:
+        class: phpbb\composer\manager
+        arguments:
+            - '@ext.composer.installer'
+            - '@cache.driver'
+            - phpbb-language
+            - LANGUAGES_
diff --git a/phpBB/config/development/config.yml b/phpBB/config/development/config.yml
index f39eb52e73..1e144d68d6 100644
--- a/phpBB/config/development/config.yml
+++ b/phpBB/config/development/config.yml
@@ -11,3 +11,7 @@ core:
         debug: true
         auto_reload: true
         enable_debug_extension: true
+
+    extensions:
+        composer_debug: true
+        composer_verbose: true
diff --git a/phpBB/download/file.php b/phpBB/download/file.php
index a9cd4a3b3c..858dfd2c32 100644
--- a/phpBB/download/file.php
+++ b/phpBB/download/file.php
@@ -99,6 +99,11 @@ if (isset($_GET['avatar']))
 	/* @var $phpbb_avatar_manager \phpbb\avatar\manager */
 	$phpbb_avatar_manager = $phpbb_container->get('avatar.manager');
 
+	if (@is_file($phpbb_root_path . $config['exts_composer_vendor_dir'] . '/autoload.php'))
+	{
+		require_once($phpbb_root_path . $config['exts_composer_vendor_dir'] . '/autoload.php');
+	}
+
 	$filename = $request->variable('avatar', '');
 	$avatar_group = false;
 	$exit = false;
diff --git a/phpBB/includes/acp/acp_extensions.php b/phpBB/includes/acp/acp_extensions.php
index c08674841c..bedd387ee3 100644
--- a/phpBB/includes/acp/acp_extensions.php
+++ b/phpBB/includes/acp/acp_extensions.php
@@ -24,23 +24,32 @@ if (!defined('IN_PHPBB'))
 
 class acp_extensions
 {
-	var $u_action;
-	var $tpl_name;
-	var $page_title;
+	public $u_action;
 
+	private $db;
+
+	/** @var  phpbb\config\config */
 	private $config;
+
+	/** @var \phpbb\template\twig\twig */
 	private $template;
 	private $user;
 	private $log;
+
+	/** @var \phpbb\request\request */
 	private $request;
 	private $phpbb_dispatcher;
-	private $ext_manager;
 
-	function main()
+	/** @var \phpbb\extension\manager */
+	private $ext_manager;
+	private $u_catalog_action;
+
+	function main($id, $mode)
 	{
 		// Start the page
-		global $config, $user, $template, $request, $phpbb_extension_manager, $phpbb_root_path, $phpbb_log, $phpbb_dispatcher;
+		global $config, $user, $template, $request, $phpbb_extension_manager, $db, $phpbb_log, $phpbb_dispatcher;
 
+		$this->db       = $db;
 		$this->config = $config;
 		$this->template = $template;
 		$this->user = $user;
@@ -49,7 +58,22 @@ class acp_extensions
 		$this->phpbb_dispatcher = $phpbb_dispatcher;
 		$this->ext_manager = $phpbb_extension_manager;
 
-		$this->user->add_lang(array('install', 'acp/extensions', 'migrator'));
+		$this->user->add_lang(['install', 'acp/extensions', 'migrator']);
+
+		switch ($mode)
+		{
+			case 'catalog':
+				$this->catalog_mode($id, $mode);
+			break;
+			default:
+				$this->main_mode($id, $mode);
+			break;
+		}
+	}
+
+	public function main_mode($id, $mode)
+	{
+		global $phpbb_extension_manager, $phpbb_container, $phpbb_admin_path, $phpEx;
 
 		$this->page_title = 'ACP_EXTENSIONS';
 
@@ -110,6 +134,8 @@ class acp_extensions
 			}
 		}
 
+		$this->u_catalog_action = append_sid("{$phpbb_admin_path}index.$phpEx", "i=$id&amp;mode=catalog");
+
 		// What are we doing?
 		switch ($action)
 		{
@@ -133,7 +159,7 @@ class acp_extensions
 					$this->config->set('extension_force_unstable', false);
 					trigger_error($this->user->lang['CONFIG_UPDATED'] . adm_back_link($this->u_action));
 				}
-				break;
+			break;
 
 			case 'list':
 			default:
@@ -143,15 +169,27 @@ class acp_extensions
 					trigger_error($this->user->lang['CONFIG_UPDATED'] . adm_back_link($this->u_action));
 				}
 
-				$this->list_enabled_exts();
-				$this->list_disabled_exts();
-				$this->list_available_exts();
+				/** @var \phpbb\composer\manager $composer_manager */
+				$composer_manager = $phpbb_container->get('ext.composer.manager');
+
+				$managed_packages = [];
+				if ($composer_manager->check_requirements())
+				{
+					$managed_packages = $composer_manager->get_managed_packages();
+				}
+
+				$this->list_enabled_exts($phpbb_extension_manager, $managed_packages);
+				$this->list_disabled_exts($phpbb_extension_manager, $managed_packages);
+				$this->list_available_exts($phpbb_extension_manager, $managed_packages);
 
 				$this->template->assign_vars(array(
 					'U_VERSIONCHECK_FORCE' 	=> $this->u_action . '&amp;action=list&amp;versioncheck_force=1',
 					'FORCE_UNSTABLE'		=> $this->config['extension_force_unstable'],
 					'U_ACTION' 				=> $this->u_action,
+					'MANAGED_EXTENSIONS'	=> $managed_packages,
+					'U_CATALOG_ACTION' 		=> $this->u_catalog_action,
 				));
+				$this->request->disable_super_globals();
 
 				$this->tpl_name = 'acp_ext_list';
 			break;
@@ -382,11 +420,340 @@ class acp_extensions
 	}
 
 	/**
-	* Lists all the enabled extensions and dumps to the template
-	*
-	* @return null
-	*/
-	public function list_enabled_exts()
+	 * Handles the catalog mode of the extensions list
+	 *
+	 * @param string $id
+	 * @param string $mode
+	 */
+	public function catalog_mode($id, $mode)
+	{
+		global $phpbb_container;
+
+		$action = $this->request->variable('action', 'list');
+
+		/** @var \phpbb\language\language $language */
+		$language = $phpbb_container->get('language');
+
+		/** @var \phpbb\composer\manager $composer_manager */
+		$composer_manager = $phpbb_container->get('ext.composer.manager');
+
+		/** @var \phpbb\extension\manager $extensions_manager */
+		$extensions_manager = $phpbb_container->get('ext.manager');
+
+		if (!$composer_manager->check_requirements())
+		{
+			$this->page_title = 'ACP_EXTENSIONS_CATALOG';
+			$this->tpl_name = 'message_body';
+
+			$this->template->assign_vars([
+				'MESSAGE_TITLE'	=> $language->lang('EXTENSIONS_CATALOG_NOT_AVAILABLE'),
+				'MESSAGE_TEXT'	=> $language->lang('EXTENSIONS_COMPOSER_NOT_WRITABLE'),
+			]);
+
+			return;
+		}
+
+		switch ($action)
+		{
+			case 'install':
+				$this->page_title = 'ACP_EXTENSIONS_INSTALL';
+
+				$extension = $this->request->variable('extension', '');
+
+				if (empty($extension))
+				{
+					redirect($this->u_action);
+				}
+
+				$formatter = new \phpbb\composer\io\html_output_formatter([
+					'warning' => new \Symfony\Component\Console\Formatter\OutputFormatterStyle('black', 'yellow')
+				]);
+
+				$composer_io = new \phpbb\composer\io\web_io($language, '', $phpbb_container->getParameter('extensions.composer.output'), $formatter);
+
+				try
+				{
+					$composer_manager->install((array) $extension, $composer_io);
+				}
+				catch (\phpbb\exception\runtime_exception $e)
+				{
+					$this->display_composer_exception($language, $e, $composer_io);
+					return;
+				}
+				$this->tpl_name = 'detailed_message_body';
+
+				$this->template->assign_vars(array(
+						'MESSAGE_TITLE'			=> $language->lang('ACP_EXTENSIONS_INSTALL'),
+						'MESSAGE_TEXT'			=> $language->lang('EXTENSIONS_INSTALLED') . adm_back_link($this->u_action),
+						'MESSAGE_DETAIL'		=> $composer_io->getOutput(),
+						'MESSAGE_DETAIL_LEGEND'	=> $language->lang('COMPOSER_OUTPUT'),
+						'S_USER_NOTICE'			=> true,
+					)
+				);
+
+			break;
+			case 'remove':
+				$this->page_title = 'ACP_EXTENSIONS_REMOVE';
+
+				$extension = $this->request->variable('extension', '');
+
+				if (empty($extension))
+				{
+					redirect($this->u_action);
+				}
+
+				$formatter = new \phpbb\composer\io\html_output_formatter([
+					'warning' => new \Symfony\Component\Console\Formatter\OutputFormatterStyle('black', 'yellow')
+				]);
+
+				$composer_io = new \phpbb\composer\io\web_io($language, '', $phpbb_container->getParameter('extensions.composer.output'), $formatter);
+
+				try
+				{
+					$composer_manager->remove((array) $extension, $composer_io);
+				}
+				catch (\phpbb\exception\runtime_exception $e)
+				{
+					$this->display_composer_exception($language, $e, $composer_io);
+					return;
+				}
+				$this->tpl_name = 'detailed_message_body';
+
+				$this->template->assign_vars(array(
+						'MESSAGE_TITLE'			=> $language->lang('ACP_EXTENSIONS_REMOVE'),
+						'MESSAGE_TEXT'			=> $language->lang('EXTENSIONS_REMOVED') . adm_back_link($this->u_action),
+						'MESSAGE_DETAIL'		=> $composer_io->getOutput(),
+						'MESSAGE_DETAIL_LEGEND'	=> $language->lang('COMPOSER_OUTPUT'),
+						'S_USER_NOTICE'			=> true,
+					)
+				);
+
+			break;
+			case 'update':
+				$this->page_title = 'ACP_EXTENSIONS_UPDATE';
+
+				$extension = $this->request->variable('extension', '');
+
+				if (empty($extension))
+				{
+					redirect($this->u_action);
+				}
+
+				$formatter = new \phpbb\composer\io\html_output_formatter([
+					'warning' => new \Symfony\Component\Console\Formatter\OutputFormatterStyle('black', 'yellow')
+				]);
+
+				$composer_io = new \phpbb\composer\io\web_io($language, '', $phpbb_container->getParameter('extensions.composer.output'), $formatter);
+
+				try
+				{
+					$composer_manager->update((array) $extension, $composer_io);
+				}
+				catch (\phpbb\exception\runtime_exception $e)
+				{
+					$this->display_composer_exception($language, $e, $composer_io);
+					return;
+				}
+				$this->tpl_name = 'detailed_message_body';
+
+				$this->template->assign_vars(array(
+						'MESSAGE_TITLE'			=> $language->lang('ACP_EXTENSIONS_UPDATE'),
+						'MESSAGE_TEXT'			=> $language->lang('EXTENSIONS_UPDATED') . adm_back_link($this->u_action),
+						'MESSAGE_DETAIL'		=> $composer_io->getOutput(),
+						'MESSAGE_DETAIL_LEGEND'	=> $language->lang('COMPOSER_OUTPUT'),
+						'S_USER_NOTICE'			=> true,
+					)
+				);
+
+			break;
+			case 'manage':
+				$this->page_title = 'ACP_EXTENSIONS_MANAGE';
+
+				$extension = $this->request->variable('extension', '');
+
+				if (empty($extension))
+				{
+					redirect($this->u_action);
+				}
+
+				$formatter = new \phpbb\composer\io\html_output_formatter([
+					'warning' => new \Symfony\Component\Console\Formatter\OutputFormatterStyle('black', 'yellow')
+				]);
+
+				$composer_io = new \phpbb\composer\io\web_io($language, '', $phpbb_container->getParameter('extensions.composer.output'), $formatter);
+
+				try
+				{
+					$composer_manager->start_managing($extension, $composer_io);
+				}
+				catch (\phpbb\exception\runtime_exception $e)
+				{
+					$this->display_composer_exception($language, $e, $composer_io);
+					return;
+				}
+				$this->tpl_name = 'detailed_message_body';
+
+				$this->template->assign_vars(array(
+						'MESSAGE_TITLE'			=> $language->lang('ACP_EXTENSIONS_MANAGE'),
+						'MESSAGE_TEXT'			=> $language->lang('EXTENSION_MANAGED_SUCCESS', $extension) . adm_back_link($this->u_action),
+						'MESSAGE_DETAIL'		=> $composer_io->getOutput(),
+						'MESSAGE_DETAIL_LEGEND'	=> $language->lang('COMPOSER_OUTPUT'),
+						'S_USER_NOTICE'			=> true,
+					)
+				);
+
+			break;
+			case 'list':
+			default:
+				if (!$this->config['exts_composer_packagist'] && $this->request->is_set('enable_packagist') && confirm_box(true))
+				{
+					$this->config->set('exts_composer_packagist', true);
+					$composer_manager->reset_cache();
+
+					trigger_error($language->lang('CONFIG_UPDATED') . adm_back_link($this->u_action));
+				}
+
+				$submit = $this->request->is_set('update');
+				if ($submit)
+				{
+					if (!check_form_key('catalog_settings'))
+					{
+						trigger_error($language->lang('FORM_INVALID') . adm_back_link($this->u_action), E_USER_WARNING);
+					}
+
+					$enable_packagist = $this->request->variable('enable_packagist', false);
+					$enable_on_install = $this->request->variable('enable_on_install', false);
+					$purge_on_remove = $this->request->variable('purge_on_remove', false);
+					$minimum_stability = $this->request->variable('minimum_stability', 'stable');
+					$repositories = array_unique(
+						array_filter(
+							array_map(
+								'trim',
+								explode("\n", $this->request->variable('repositories', ''))
+							)
+						)
+					);
+
+					$previous_minimum_stability = $this->config['exts_composer_minimum_stability'];
+					$previous_repositories = $this->config['exts_composer_repositories'];
+					$previous_enable_packagist = $this->config['exts_composer_packagist'];
+
+					$this->config->set('exts_composer_enable_on_install', $enable_on_install);
+					$this->config->set('exts_composer_purge_on_remove', $purge_on_remove);
+					$this->config->set('exts_composer_minimum_stability', $minimum_stability);
+					$this->config->set('exts_composer_repositories', json_encode($repositories, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES));
+
+					if ($minimum_stability != $previous_minimum_stability
+						|| $repositories != $previous_repositories
+						|| $enable_packagist != $previous_enable_packagist)
+					{
+						$composer_manager->reset_cache();
+					}
+
+					if (!$this->config['exts_composer_packagist'] && $enable_packagist)
+					{
+						$s_hidden_fields = build_hidden_fields(array(
+							'enable_packagist'	=> $enable_packagist
+						));
+
+						confirm_box(false, $language->lang('ENABLE_PACKAGIST_CONFIRM'), $s_hidden_fields);
+					}
+					else
+					{
+						$this->config->set('exts_composer_packagist', $enable_packagist);
+						trigger_error($language->lang('CONFIG_UPDATED') . adm_back_link($this->u_action));
+					}
+				}
+
+				/** @var \phpbb\composer\extension_manager $manager */
+				$manager = $phpbb_container->get('ext.composer.manager');
+
+				/** @var \phpbb\pagination $pagination */
+				$pagination = $phpbb_container->get('pagination');
+
+				$start = $this->request->variable('start', 0);
+				$base_url = $this->u_action;
+
+				$available_extensions = $manager->get_available_packages();
+				$managed_packages = $manager->get_managed_packages();
+
+				$extensions = array_slice($available_extensions, $start, 20);
+
+				$pagination->generate_template_pagination($base_url, 'pagination', 'start', count($available_extensions), 20, $start);
+
+				$this->page_title = 'ACP_EXTENSIONS_CATALOG';
+				$this->tpl_name = 'acp_ext_catalog';
+
+				$this->template->assign_vars([
+					'extensions'			=> $extensions,
+					'managed_extensions'	=> array_keys($managed_packages),
+					'installed_extensions'	=> array_keys($extensions_manager->all_available()),
+					'U_ACTION'				=> $this->u_action,
+					'settings' => [
+						'enable_packagist'	=> $this->config['exts_composer_packagist'],
+						'enable_on_install'	=> $this->config['exts_composer_enable_on_install'],
+						'purge_on_remove'	=> $this->config['exts_composer_purge_on_remove'],
+						'minimum_stability'	=> $this->config['exts_composer_minimum_stability'],
+						'stabilities'		=> array_keys(\Composer\Package\BasePackage::$stabilities),
+						'repositories'		=> json_decode($this->config['exts_composer_repositories'], true),
+					],
+				]);
+
+				add_form_key('catalog_settings');
+
+			break;
+		}
+	}
+
+	/**
+	 * Display an exception raised by the composer manager
+	 *
+	 * @param \phpbb\language\language           $language
+	 * @param \phpbb\exception\runtime_exception $e
+	 * @param \phpbb\composer\io\web_io          $composer_io
+	 */
+	private function display_composer_exception(\phpbb\language\language $language, \phpbb\exception\runtime_exception $e, \phpbb\composer\io\web_io $composer_io)
+	{
+		$this->tpl_name = 'detailed_message_body';
+
+		if ($e->getPrevious())
+		{
+			$message_title = $language->lang_array($e->getMessage(), $e->get_parameters());
+
+			if ($e->getPrevious() instanceof \phpbb\exception\exception_interface)
+			{
+				$message_text  = $language->lang_array($e->getPrevious()->getMessage(), $e->getPrevious()->get_parameters()) . adm_back_link($this->u_action);
+			}
+			else
+			{
+				$message_text = $e->getPrevious()->getMessage() . adm_back_link($this->u_action);
+			}
+		}
+		else
+		{
+			$message_title = $language->lang('INFORMATION');
+			$message_text  = $language->lang_array($e->getMessage(), $e->get_parameters()) . adm_back_link($this->u_action);
+		}
+
+		$this->template->assign_vars(array(
+				'MESSAGE_TITLE'			=> $message_title,
+				'MESSAGE_TEXT'			=> $message_text,
+				'MESSAGE_DETAIL'		=> $composer_io->getOutput(),
+				'MESSAGE_DETAIL_LEGEND'	=> $language->lang('COMPOSER_OUTPUT'),
+				'S_USER_ERROR'			=> true,
+			)
+		);
+	}
+
+	/**
+	 * Lists all the enabled extensions and dumps to the template
+	 *
+	 * @param \phpbb\extension\manager  $phpbb_extension_manager     An instance of the extension manager
+	 * @param array                     $managed_packages            List of managed packages
+	 *
+	 * @return null
+	 */
+	public function list_enabled_exts(\phpbb\extension\manager $phpbb_extension_manager, array $managed_packages)
 	{
 		$enabled_extension_meta_data = array();
 
@@ -400,6 +767,7 @@ class acp_extensions
 				$enabled_extension_meta_data[$name] = array(
 					'META_DISPLAY_NAME' => $md_manager->get_metadata('display-name'),
 					'META_VERSION' => $meta['version'],
+					'META_NAME' => $md_manager->get_metadata('name'),
 				);
 
 				if (isset($meta['extra']['version-check']))
@@ -449,15 +817,29 @@ class acp_extensions
 			$this->output_actions('enabled', array(
 				'DISABLE'		=> $this->u_action . '&amp;action=disable_pre&amp;ext_name=' . urlencode($name),
 			));
+
+			if (isset($managed_packages[$block_vars['META_NAME']]))
+			{
+				$this->output_actions('enabled', [
+					'UPDATE' => $this->u_catalog_action . '&amp;action=update&amp;extension=' . urlencode($block_vars['META_NAME']),
+					'REMOVE' => [
+						'url' => $this->u_catalog_action . '&amp;action=remove&amp;extension=' . urlencode($block_vars['META_NAME']),
+						'color' => '#BC2A4D;',
+					]
+				]);
+			}
 		}
 	}
 
 	/**
-	* Lists all the disabled extensions and dumps to the template
-	*
-	* @return null
-	*/
-	public function list_disabled_exts()
+	 * Lists all the disabled extensions and dumps to the template
+	 *
+	 * @param \phpbb\extension\manager  $phpbb_extension_manager     An instance of the extension manager
+	 * @param array                     $managed_packages            List of managed packages
+	 *
+	 * @return null
+	 */
+	public function list_disabled_exts(\phpbb\extension\manager $phpbb_extension_manager, array $managed_packages)
 	{
 		$disabled_extension_meta_data = array();
 
@@ -471,6 +853,7 @@ class acp_extensions
 				$disabled_extension_meta_data[$name] = array(
 					'META_DISPLAY_NAME' => $md_manager->get_metadata('display-name'),
 					'META_VERSION' => $meta['version'],
+					'META_NAME' => $md_manager->get_metadata('name'),
 				);
 
 				if (isset($meta['extra']['version-check']))
@@ -518,15 +901,29 @@ class acp_extensions
 				'ENABLE'		=> $this->u_action . '&amp;action=enable_pre&amp;ext_name=' . urlencode($name),
 				'DELETE_DATA'	=> $this->u_action . '&amp;action=delete_data_pre&amp;ext_name=' . urlencode($name),
 			));
+
+			if (isset($managed_packages[$block_vars['META_NAME']]))
+			{
+				$this->output_actions('disabled', [
+					'UPDATE' => $this->u_catalog_action . '&amp;action=update&amp;extension=' . urlencode($block_vars['META_NAME']),
+					'REMOVE' => [
+						'url' => $this->u_catalog_action . '&amp;action=remove&amp;extension=' . urlencode($block_vars['META_NAME']),
+						'color' => '#BC2A4D;',
+					]
+				]);
+			}
 		}
 	}
 
 	/**
-	* Lists all the available extensions and dumps to the template
-	*
-	* @return null
-	*/
-	public function list_available_exts()
+	 * Lists all the available extensions and dumps to the template
+	 *
+	 * @param \phpbb\extension\manager  $phpbb_extension_manager     An instance of the extension manager
+	 * @param array                     $managed_packages            List of managed packages
+	 *
+	 * @return null
+	 */
+	public function list_available_exts(\phpbb\extension\manager $phpbb_extension_manager, array $managed_packages)
 	{
 		$uninstalled = array_diff_key($this->ext_manager->all_available(), $this->ext_manager->all_configured());
 
@@ -542,6 +939,7 @@ class acp_extensions
 				$available_extension_meta_data[$name] = array(
 					'META_DISPLAY_NAME' => $md_manager->get_metadata('display-name'),
 					'META_VERSION' => $meta['version'],
+					'META_NAME' => $md_manager->get_metadata('name'),
 				);
 
 				if (isset($meta['extra']['version-check']))
@@ -595,13 +993,26 @@ class acp_extensions
 	*/
 	private function output_actions($block, $actions)
 	{
-		foreach ($actions as $lang => $url)
+		foreach ($actions as $lang => $options)
 		{
-			$this->template->assign_block_vars($block . '.actions', array(
+			$url = $options;
+			if (is_array($options))
+			{
+				$url = $options['url'];
+			}
+
+			$vars = array(
 				'L_ACTION'			=> $this->user->lang('EXTENSION_' . $lang),
 				'L_ACTION_EXPLAIN'	=> (isset($this->user->lang['EXTENSION_' . $lang . '_EXPLAIN'])) ? $this->user->lang('EXTENSION_' . $lang . '_EXPLAIN') : '',
 				'U_ACTION'			=> $url,
-			));
+			);
+
+			if (isset($options['color']))
+			{
+				$vars['COLOR'] = $options['color'];
+			}
+
+			$this->template->assign_block_vars($block . '.actions', $vars);
 		}
 	}
 
diff --git a/phpBB/includes/acp/info/acp_extensions.php b/phpBB/includes/acp/info/acp_extensions.php
index 9adcd543b9..f555d0fa8c 100644
--- a/phpBB/includes/acp/info/acp_extensions.php
+++ b/phpBB/includes/acp/info/acp_extensions.php
@@ -20,6 +20,7 @@ class acp_extensions_info
 			'title'		=> 'ACP_EXTENSION_MANAGEMENT',
 			'modes'		=> array(
 				'main'		=> array('title' => 'ACP_EXTENSIONS', 'auth' => 'acl_a_extensions', 'cat' => array('ACP_EXTENSION_MANAGEMENT')),
+				'catalog'	=> array('title' => 'ACP_EXTENSIONS_CATALOG', 'auth' => 'acl_a_extensions', 'cat' => array('ACP_EXTENSION_MANAGEMENT')),
 			),
 		);
 	}
diff --git a/phpBB/includes/functions.php b/phpBB/includes/functions.php
index 15b35ae646..c16792225d 100644
--- a/phpBB/includes/functions.php
+++ b/phpBB/includes/functions.php
@@ -4324,6 +4324,9 @@ function page_header($page_title = '', $display_online_list = false, $item_id =
 	$controller_helper = $phpbb_container->get('controller.helper');
 	$notification_mark_hash = generate_link_hash('mark_all_notifications_read');
 
+	$phpbb_version_parts = explode('.', PHPBB_VERSION, 3);
+	$phpbb_major = $phpbb_version_parts[0] . '.' . $phpbb_version_parts[1];
+
 	// The following assigns all _common_ variables that may be used at any point in a template.
 	$template->assign_vars(array(
 		'SITENAME'						=> $config['sitename'],
@@ -4357,6 +4360,8 @@ function page_header($page_title = '', $display_online_list = false, $item_id =
 		'SESSION_ID'		=> $user->session_id,
 		'ROOT_PATH'			=> $web_path,
 		'BOARD_URL'			=> $board_url,
+		'PHPBB_VERSION'		=> PHPBB_VERSION,
+		'PHPBB_MAJOR'		=> $phpbb_major,
 
 		'L_LOGIN_LOGOUT'	=> $l_login_logout,
 		'L_INDEX'			=> ($config['board_index_text'] !== '') ? $config['board_index_text'] : $user->lang['FORUM_INDEX'],
diff --git a/phpBB/includes/functions_acp.php b/phpBB/includes/functions_acp.php
index 8bf42aa36e..c79a84f8d4 100644
--- a/phpBB/includes/functions_acp.php
+++ b/phpBB/includes/functions_acp.php
@@ -66,6 +66,9 @@ function adm_page_header($page_title)
 		}
 	}
 
+	$phpbb_version_parts = explode('.', PHPBB_VERSION, 3);
+	$phpbb_major = $phpbb_version_parts[0] . '.' . $phpbb_version_parts[1];
+
 	$template->assign_vars(array(
 		'PAGE_TITLE'			=> $page_title,
 		'USERNAME'				=> $user->data['username'],
@@ -75,6 +78,8 @@ function adm_page_header($page_title)
 		'SESSION_ID'			=> $user->session_id,
 		'ROOT_PATH'				=> $phpbb_root_path,
 		'ADMIN_ROOT_PATH'		=> $phpbb_admin_path,
+		'PHPBB_VERSION'			=> PHPBB_VERSION,
+		'PHPBB_MAJOR'			=> $phpbb_major,
 
 		'U_LOGOUT'				=> append_sid("{$phpbb_root_path}ucp.$phpEx", 'mode=logout'),
 		'U_ADM_LOGOUT'			=> append_sid("{$phpbb_admin_path}index.$phpEx", 'action=admlogout'),
diff --git a/phpBB/install/schemas/schema_data.sql b/phpBB/install/schemas/schema_data.sql
index fe62484afb..c4eff64c14 100644
--- a/phpBB/install/schemas/schema_data.sql
+++ b/phpBB/install/schemas/schema_data.sql
@@ -281,6 +281,12 @@ INSERT INTO phpbb_config (config_name, config_value) VALUES ('use_system_cron',
 INSERT INTO phpbb_config (config_name, config_value) VALUES ('version', '3.3.0-a1-dev');
 INSERT INTO phpbb_config (config_name, config_value) VALUES ('warnings_expire_days', '90');
 INSERT INTO phpbb_config (config_name, config_value) VALUES ('warnings_gc', '14400');
+INSERT INTO phpbb_config (config_name, config_value) VALUES ('exts_composer_repositories', '[]');
+INSERT INTO phpbb_config (config_name, config_value) VALUES ('exts_composer_packagist', '1');
+INSERT INTO phpbb_config (config_name, config_value) VALUES ('exts_composer_json_file', 'composer-ext.json');
+INSERT INTO phpbb_config (config_name, config_value) VALUES ('exts_composer_vendor_dir', 'vendor-ext/');
+INSERT INTO phpbb_config (config_name, config_value) VALUES ('exts_composer_enable_on_install', '0');
+INSERT INTO phpbb_config (config_name, config_value) VALUES ('exts_composer_purge_on_remove', '1');
 
 INSERT INTO phpbb_config (config_name, config_value, is_dynamic) VALUES ('cache_last_gc', '0', 1);
 INSERT INTO phpbb_config (config_name, config_value, is_dynamic) VALUES ('cron_lock', '0', 1);
diff --git a/phpBB/language/en/acp/common.php b/phpBB/language/en/acp/common.php
index 9be3cc9676..6939197034 100644
--- a/phpBB/language/en/acp/common.php
+++ b/phpBB/language/en/acp/common.php
@@ -88,6 +88,11 @@ $lang = array_merge($lang, array(
 	'ACP_EXTENSION_GROUPS'		=> 'Manage attachment extension groups',
 	'ACP_EXTENSION_MANAGEMENT'	=> 'Extension management',
 	'ACP_EXTENSIONS'			=> 'Manage extensions',
+	'ACP_EXTENSIONS_CATALOG'	=> 'Extensions catalog',
+	'ACP_EXTENSIONS_INSTALL'	=> 'Install extensions',
+	'ACP_EXTENSIONS_REMOVE'		=> 'Remove extensions',
+	'ACP_EXTENSIONS_UPDATE'		=> 'Update extensions',
+	'ACP_EXTENSIONS_MANAGE'		=> 'Manage extension automatically',
 
 	'ACP_FORUM_BASED_PERMISSIONS'	=> 'Forum based permissions',
 	'ACP_FORUM_LOGS'				=> 'Forum logs',
@@ -240,6 +245,17 @@ $lang = array_merge($lang, array(
 	'EXCEPTION' => 'Exception',
 
 	'COLOUR_SWATCH'			=> 'Web-safe colour swatch',
+
+	'COMPOSER_UNSUPPORTED_OPERATION'	=> 'Operation unsupported for the package type “%s”.',
+	'COMPOSER_UPDATING_DEPENDENCIES'	=> 'Updating packages',
+	'COMPOSER_LOADING_REPOSITORIES'		=> 'Loading remote repositories with package information',
+	'COMPOSER_ERROR_CONFLICT'			=> 'Your requirements could not be resolved to an installable set of packages.',
+	'COMPOSER_REPOSITORY_UNAVAILABLE'	=> 'An error occurred while fetching the repository %s.',
+	'COMPOSER_INSTALLING_PACKAGE'		=> '  - Installing %1$s (%2$s)',
+	'COMPOSER_DELETING'					=> '  - Deleting %s',
+	'COMPOSER_UPDATE_NOTHING'			=> 'Nothing to update',
+	'COMPOSER_OUTPUT'					=> 'Composer output',
+
 	'CONFIG_UPDATED'		=> 'Configuration updated successfully.',
 	'CRON_LOCK_ERROR'		=> 'Could not obtain cron lock.',
 	'CRON_NO_SUCH_TASK'		=> 'Could not find cron task “%s”.',
diff --git a/phpBB/language/en/acp/extensions.php b/phpBB/language/en/acp/extensions.php
index a96a7a2a2b..c6eb147b86 100644
--- a/phpBB/language/en/acp/extensions.php
+++ b/phpBB/language/en/acp/extensions.php
@@ -35,6 +35,22 @@ if (empty($lang) || !is_array($lang))
 // in a url you again do not need to specify an order e.g., 'Click %sHERE%s' is fine
 
 $lang = array_merge($lang, array(
+
+	'EXTENSION_ALREADY_INSTALLED'				=> 'The “%s” extension has already been installed.',
+	'EXTENSION_ALREADY_INSTALLED_MANUALLY'		=> 'The “%s” extension has already been installed manually.',
+	'EXTENSION_ALREADY_MANAGED'					=> 'The “%s” extension is already managed.',
+	'EXTENSION_CANNOT_MANAGE_FILESYSTEM_ERROR'	=> 'The “%s” extension cannot be managed because the existing files could not be removed from the filesystem.',
+	'EXTENSION_CANNOT_MANAGE_INSTALL_ERROR'		=> 'The “%s” extension could not be installed. The prior installation of this extension has been restored.',
+	'EXTENSION_MANAGED_WITH_CLEAN_ERROR'		=> 'The “%1$s” extension has been installed but an error occurred and the old files could not be removed. You might want to delete the “%2$s” files manually.',
+	'EXTENSION_MANAGED_WITH_ENABLE_ERROR'		=> 'The “%s” extension has been installed but an error occurred while enabling it.',
+	'EXTENSION_NOT_INSTALLED'					=> 'The “%s” extension is not installed.',
+
+	'ENABLING_EXTENSIONS'	=> 'Enabling extensions',
+	'DISABLING_EXTENSIONS'	=> 'Disabling extensions',
+
+	'EXTENSIONS_CATALOG'			=> 'Extensions Catalog',
+	'EXTENSIONS_CATALOG_EXPLAIN'	=> 'Here you can browse all of the extensions available for your phpBB board. Extensions can easily be installed or removed with just a click. Adjust the settings to allow instant enabling and purging of extensions.',
+
 	'EXTENSION'					=> 'Extension',
 	'EXTENSIONS'				=> 'Extensions',
 	'EXTENSIONS_ADMIN'			=> 'Extensions Manager',
@@ -43,7 +59,6 @@ $lang = array_merge($lang, array(
 	'EXTENSION_NOT_AVAILABLE'	=> 'The selected extension is not available for this board, please verify your phpBB and PHP versions are allowed (see the details page).',
 	'EXTENSION_DIR_INVALID'		=> 'The selected extension has an invalid directory structure and cannot be enabled.',
 	'EXTENSION_NOT_ENABLEABLE'	=> 'The selected extension cannot be enabled, please verify the extension’s requirements.',
-	'EXTENSION_NOT_INSTALLED'	=> 'The extension %s is not available. Please check that you have installed it correctly.',
 
 	'DETAILS'				=> 'Details',
 
@@ -53,6 +68,8 @@ $lang = array_merge($lang, array(
 	'EXTENSION_DELETE_DATA'	=> 'Delete data',
 	'EXTENSION_DISABLE'		=> 'Disable',
 	'EXTENSION_ENABLE'		=> 'Enable',
+	'EXTENSION_UPDATE'		=> 'Update',
+	'EXTENSION_REMOVE'		=> 'Remove',
 
 	'EXTENSION_DELETE_DATA_EXPLAIN'	=> 'Deleting an extension’s data removes all of its data and settings. The extension files are retained so it can be enabled again.',
 	'EXTENSION_DISABLE_EXPLAIN'		=> 'Disabling an extension retains its files, data and settings but removes any functionality added by the extension.',
@@ -94,6 +111,9 @@ $lang = array_merge($lang, array(
 	'EXTENSION_ENABLE_CONFIRM'		=> 'Are you sure that you wish to enable the “%s” extension?',
 	'EXTENSION_FORCE_UNSTABLE_CONFIRM'	=> 'Are you sure that you wish to force the use of unstable version?',
 
+	'INSTALLED'				=> 'Installed',
+	'INSTALLED_MANUALLY'	=> 'Installed manually',
+
 	'RETURN_TO_EXTENSION_LIST'	=> 'Return to the extension list',
 
 	'EXT_DETAILS'			=> 'Extension Details',
@@ -130,4 +150,32 @@ $lang = array_merge($lang, array(
 
 	'META_FIELD_NOT_SET'	=> 'Required meta field %s has not been set.',
 	'META_FIELD_INVALID'	=> 'Meta field %s is invalid.',
+
+	'EXTENSIONS_CATALOG_SETTINGS'	=> 'Extensions catalog settings',
+	'ENABLE_ON_INSTALL'				=> 'Enable extensions while installing',
+	'PURGE_ON_REMOVE'				=> 'Purge extensions while removing',
+	'ENABLE_PACKAGIST'				=> 'Search packagist',
+	'ENABLE_PACKAGIST_EXPLAIN'		=> 'Search packagist for phpBB extensions. Beware that packagist may contain extensions not validated by the phpBB Extension Customisations Team.',
+	'ENABLE_PACKAGIST_CONFIRM'		=> 'Are you sure you want to search packagist?',
+	'COMPOSER_REPOSITORIES'			=> 'Repositories',
+	'COMPOSER_REPOSITORIES_EXPLAIN'	=> 'Add URLs to Composer repositories of phpBB extensions to search here, one per line (must be the base url of the packages.json file).',
+	'NO_EXTENSION_AVAILABLE'		=> 'There are no extension available for your board',
+
+	'EXTENSION_MANAGED_SUCCESS'		=> 'The extension %s is now being managed automatically.',
+	'EXTENSIONS_INSTALLED'			=> 'Extensions successfully installed.',
+	'EXTENSIONS_REMOVED'			=> 'Extensions successfully removed.',
+	'EXTENSIONS_UPDATED'			=> 'Extensions successfully updated.',
+
+	'EXTENSIONS_CATALOG_NOT_AVAILABLE'	=> 'The extensions catalog is not available',
+	'EXTENSIONS_COMPOSER_NOT_WRITABLE'	=> 'In order to use the catalog, the following files and directories must be writable: ext/ vendor-ext/ composer-ext.json and composer-ext.lock',
+
+	'STABILITY_STABLE'	=> 'stable',
+	'STABILITY_RC'		=> 'RC',
+	'STABILITY_BETA'	=> 'beta',
+	'STABILITY_ALPHA'	=> 'alpha',
+	'STABILITY_DEV'		=> 'dev',
+
+	'COMPOSER_MINIMUM_STABILITY'			=> 'Minimum stability',
+	'COMPOSER_MINIMUM_STABILITY_EXPLAIN'	=> 'Always use <samp>stable</samp> versions on a live forum. Non-stable versions may still be in development and could cause unexpected problems with your forum and should only be used for development purposes in local or staging environments.',
+
 ));
diff --git a/phpBB/language/en/cli.php b/phpBB/language/en/cli.php
index 2f969ceede..6046910455 100644
--- a/phpBB/language/en/cli.php
+++ b/phpBB/language/en/cli.php
@@ -157,6 +157,18 @@ $lang = array_merge($lang, array(
 		1	=> 'Re-cleaning complete. %d username was cleaned.',
 		2	=> 'Re-cleaning complete. %d usernames were cleaned.',
 	],
+
+	'CLI_DESCRIPTION_EXTENSION_MANAGE'					=> 'Manages an extension',
+	'CLI_DESCRIPTION_EXTENSION_MANAGE_ARGUMENT'			=> 'Extension to manage',
+	'CLI_DESCRIPTION_EXTENSION_INSTALL'					=> 'Install the specified extension(s).',
+	'CLI_DESCRIPTION_EXTENSION_INSTALL_OPTION_ENABLE'	=> 'Enable extension(s) after installation',
+	'CLI_DESCRIPTION_EXTENSION_INSTALL_ARGUMENT'		=> 'Extension(s) to install, e.g.: vendor/package',
+	'CLI_DESCRIPTION_EXTENSION_LIST_AVAILABLE'			=> 'List extensions available for installation.',
+	'CLI_DESCRIPTION_EXTENSION_REMOVE'					=> 'Remove the specified extension(s).',
+	'CLI_DESCRIPTION_EXTENSION_REMOVE_OPTION_PURGE'		=> 'Purge extension(s) when removing them',
+	'CLI_DESCRIPTION_EXTENSION_REMOVE_ARGUMENT'			=> 'Extension(s) to remove, e.g.: vendor/package',
+	'CLI_DESCRIPTION_EXTENSION_UPDATE'					=> 'Update the specified extension(s).',
+	'CLI_DESCRIPTION_EXTENSION_UPDATE_ARGUMENT'			=> 'Extension(s) to update, e.g.: vendor/package',
 ));
 
 // Additional help for commands.
diff --git a/phpBB/language/en/common.php b/phpBB/language/en/common.php
index 709b7d9731..e2198655c9 100644
--- a/phpBB/language/en/common.php
+++ b/phpBB/language/en/common.php
@@ -153,6 +153,7 @@ $lang = array_merge($lang, array(
 	'BYTES_SHORT'			=> 'B',
 
 	'CANCEL'				=> 'Cancel',
+	'CANNOT_RENAME_FILE'	=> 'Cannot rename %s',
 	'CHANGE'				=> 'Change',
 	'CHANGE_FONT_SIZE'		=> 'Change font size',
 	'CHANGING_PREFERENCES'	=> 'Changing board preferences',
diff --git a/phpBB/phpbb/composer/exception/managed_with_clean_error_exception_exception.php b/phpBB/phpbb/composer/exception/managed_with_clean_error_exception_exception.php
new file mode 100644
index 0000000000..2339fa4096
--- /dev/null
+++ b/phpBB/phpbb/composer/exception/managed_with_clean_error_exception_exception.php
@@ -0,0 +1,35 @@
+<?php
+/**
+ *
+ * This file is part of the phpBB Forum Software package.
+ *
+ * @copyright (c) phpBB Limited <https://www.phpbb.com>
+ * @license GNU General Public License, version 2 (GPL-2.0)
+ *
+ * For full copyright and license information, please see
+ * the docs/CREDITS.txt file.
+ *
+ */
+
+namespace phpbb\composer\exception;
+
+/**
+ * Packaged managed with success but error occurred when cleaning the filesystem
+ */
+class managed_with_clean_error_exception extends managed_with_error_exception
+{
+	/**
+	 * Constructor
+	 *
+	 * @param string		$prefix		The language string prefix
+	 * @param string		$message	The Exception message to throw (must be a language variable).
+	 * @param array			$parameters	The parameters to use with the language var.
+	 * @param \Exception	$previous	The previous runtime_exception used for the runtime_exception chaining.
+	 * @param integer		$code		The Exception code.
+	 */
+	public function __construct($prefix, $message = '', array $parameters = [], \Exception $previous = null, $code = 0)
+	{
+		parent::__construct($prefix . $message, $parameters, $previous, $code);
+	}
+
+}
diff --git a/phpBB/phpbb/composer/exception/managed_with_enable_error_exception.php b/phpBB/phpbb/composer/exception/managed_with_enable_error_exception.php
new file mode 100644
index 0000000000..7ef7a42df3
--- /dev/null
+++ b/phpBB/phpbb/composer/exception/managed_with_enable_error_exception.php
@@ -0,0 +1,35 @@
+<?php
+/**
+ *
+ * This file is part of the phpBB Forum Software package.
+ *
+ * @copyright (c) phpBB Limited <https://www.phpbb.com>
+ * @license GNU General Public License, version 2 (GPL-2.0)
+ *
+ * For full copyright and license information, please see
+ * the docs/CREDITS.txt file.
+ *
+ */
+
+namespace phpbb\composer\exception;
+
+/**
+ * Packaged managed with success but error occurred when re-enabling the extension
+ */
+class managed_with_enable_error_exception extends managed_with_error_exception
+{
+	/**
+	 * Constructor
+	 *
+	 * @param string		$prefix		The language string prefix
+	 * @param string		$message	The Exception message to throw (must be a language variable).
+	 * @param array			$parameters	The parameters to use with the language var.
+	 * @param \Exception	$previous	The previous runtime_exception used for the runtime_exception chaining.
+	 * @param integer		$code		The Exception code.
+	 */
+	public function __construct($prefix, $message = '', array $parameters = [], \Exception $previous = null, $code = 0)
+	{
+		parent::__construct($prefix . $message, $parameters, $previous, $code);
+	}
+
+}
diff --git a/phpBB/phpbb/composer/exception/managed_with_error_exception.php b/phpBB/phpbb/composer/exception/managed_with_error_exception.php
new file mode 100644
index 0000000000..9e7c67580e
--- /dev/null
+++ b/phpBB/phpbb/composer/exception/managed_with_error_exception.php
@@ -0,0 +1,35 @@
+<?php
+/**
+ *
+ * This file is part of the phpBB Forum Software package.
+ *
+ * @copyright (c) phpBB Limited <https://www.phpbb.com>
+ * @license GNU General Public License, version 2 (GPL-2.0)
+ *
+ * For full copyright and license information, please see
+ * the docs/CREDITS.txt file.
+ *
+ */
+
+namespace phpbb\composer\exception;
+
+/**
+ * Packaged managed with success but errored at some point
+ */
+class managed_with_error_exception extends runtime_exception
+{
+	/**
+	 * Constructor
+	 *
+	 * @param string		$prefix		The language string prefix
+	 * @param string		$message	The Exception message to throw (must be a language variable).
+	 * @param array			$parameters	The parameters to use with the language var.
+	 * @param \Exception	$previous	The previous runtime_exception used for the runtime_exception chaining.
+	 * @param integer		$code		The Exception code.
+	 */
+	public function __construct($prefix, $message = '', array $parameters = [], \Exception $previous = null, $code = 0)
+	{
+		parent::__construct($prefix . $message, $parameters, $previous, $code);
+	}
+
+}
diff --git a/phpBB/phpbb/composer/exception/runtime_exception.php b/phpBB/phpbb/composer/exception/runtime_exception.php
new file mode 100644
index 0000000000..eb92759318
--- /dev/null
+++ b/phpBB/phpbb/composer/exception/runtime_exception.php
@@ -0,0 +1,37 @@
+<?php
+/**
+ *
+ * This file is part of the phpBB Forum Software package.
+ *
+ * @copyright (c) phpBB Limited <https://www.phpbb.com>
+ * @license GNU General Public License, version 2 (GPL-2.0)
+ *
+ * For full copyright and license information, please see
+ * the docs/CREDITS.txt file.
+ *
+ */
+
+namespace phpbb\composer\exception;
+
+use phpbb\exception\runtime_exception as base;
+
+/**
+ * Base class for exceptions thrown when managing packages through composer
+ */
+class runtime_exception extends base
+{
+	/**
+	 * Constructor
+	 *
+	 * @param string		$prefix		The language string prefix
+	 * @param string		$message	The Exception message to throw (must be a language variable).
+	 * @param array			$parameters	The parameters to use with the language var.
+	 * @param \Exception	$previous	The previous runtime_exception used for the runtime_exception chaining.
+	 * @param integer		$code		The Exception code.
+	 */
+	public function __construct($prefix, $message = '', array $parameters = [], \Exception $previous = null, $code = 0)
+	{
+		parent::__construct($prefix . $message, $parameters, $previous, $code);
+	}
+
+}
diff --git a/phpBB/phpbb/composer/extension_manager.php b/phpBB/phpbb/composer/extension_manager.php
new file mode 100644
index 0000000000..96250e9dd3
--- /dev/null
+++ b/phpBB/phpbb/composer/extension_manager.php
@@ -0,0 +1,316 @@
+<?php
+/**
+ *
+ * This file is part of the phpBB Forum Software package.
+ *
+ * @copyright (c) phpBB Limited <https://www.phpbb.com>
+ * @license GNU General Public License, version 2 (GPL-2.0)
+ *
+ * For full copyright and license information, please see
+ * the docs/CREDITS.txt file.
+ *
+ */
+
+namespace phpbb\composer;
+
+use Composer\IO\IOInterface;
+use phpbb\cache\driver\driver_interface;
+use phpbb\composer\exception\managed_with_clean_error_exception;
+use phpbb\composer\exception\managed_with_enable_error_exception;
+use phpbb\composer\exception\runtime_exception;
+use phpbb\config\config;
+use phpbb\extension\manager as ext_manager;
+use phpbb\filesystem\exception\filesystem_exception;
+use phpbb\filesystem\filesystem;
+
+/**
+ * Class to safely manage extensions through composer.
+ */
+class extension_manager extends manager
+{
+	/**
+	 * @var \phpbb\extension\manager
+	 */
+	protected $extension_manager;
+
+	/**
+	 * @var \phpbb\filesystem\filesystem
+	 */
+	protected $filesystem;
+
+	/**
+	 * @var array
+	 */
+	private $enabled_extensions;
+
+	/**
+	 * @var bool Enables extensions when installing them?
+	 */
+	private $enable_on_install = false;
+
+	/**
+	 * @var bool Purges extensions data when removing them?
+	 */
+	private $purge_on_remove = true;
+
+	/**
+	 * @param installer			$installer			Installer object
+	 * @param driver_interface	$cache				Cache object
+	 * @param ext_manager		$extension_manager	phpBB extension manager
+	 * @param filesystem		$filesystem			Filesystem object
+	 * @param string			$package_type		Composer type of managed packages
+	 * @param string			$exception_prefix	Exception prefix to use
+	 * @param string			$root_path			phpBB root path
+	 * @param config			$config				Config object
+	 */
+	public function __construct(installer $installer, driver_interface $cache, ext_manager $extension_manager, filesystem $filesystem, $package_type, $exception_prefix, $root_path, config $config = null)
+	{
+		$this->extension_manager = $extension_manager;
+		$this->filesystem = $filesystem;
+		$this->root_path = $root_path;
+
+		if ($config)
+		{
+			$this->enable_on_install = (bool) $config['exts_composer_enable_on_install'];
+			$this->purge_on_remove   = (bool) $config['exts_composer_purge_on_remove'];
+		}
+
+		parent::__construct($installer, $cache, $package_type, $exception_prefix);
+	}
+
+	/**
+	 * {@inheritdoc}
+	 */
+	public function pre_install(array $packages, IOInterface $io = null)
+	{
+		$installed_manually = array_intersect(array_keys($this->extension_manager->all_available()), array_keys($packages));
+		if (count($installed_manually) !== 0)
+		{
+			throw new runtime_exception($this->exception_prefix, 'ALREADY_INSTALLED_MANUALLY', [implode('|', array_keys($installed_manually))]);
+		}
+	}
+
+	/**
+	 * {@inheritdoc}
+	 */
+	public function post_install(array $packages, IOInterface $io = null)
+	{
+		if ($this->enable_on_install)
+		{
+			$io->writeError([['ENABLING_EXTENSIONS', [], 1]], true);
+			foreach ($packages as $package => $version)
+			{
+				try
+				{
+					$this->extension_manager->enable($package);
+				}
+				catch (\phpbb\exception\runtime_exception $e)
+				{
+					$io->writeError([[$e->getMessage(), $e->get_parameters(), 4]], true);
+				}
+				catch (\Exception $e)
+				{
+					$io->writeError([[$e->getMessage(), [], 4]], true);
+				}
+			}
+		}
+	}
+
+	/**
+	 * {@inheritdoc}
+	 */
+	protected function pre_update(array $packages, IOInterface $io = null)
+	{
+		$io->writeError([['DISABLING_EXTENSIONS', [], 1]], true);
+		$this->enabled_extensions = [];
+		foreach ($packages as $package => $version)
+		{
+			try
+			{
+				if ($this->extension_manager->is_enabled($package))
+				{
+					$this->enabled_extensions[] = $package;
+					$this->extension_manager->disable($package);
+				}
+			}
+			catch (\phpbb\exception\runtime_exception $e)
+			{
+				$io->writeError([[$e->getMessage(), $e->get_parameters(), 4]], true);
+			}
+			catch (\Exception $e)
+			{
+				$io->writeError([[$e->getMessage(), [], 4]], true);
+			}
+		}
+	}
+
+	/**
+	 * {@inheritdoc}
+	 */
+	protected function post_update(array $packages, IOInterface $io = null)
+	{
+		$io->writeError([['ENABLING_EXTENSIONS', [], 1]], true);
+		foreach ($this->enabled_extensions as $package)
+		{
+			try
+			{
+				$this->extension_manager->enable($package);
+			}
+			catch (\phpbb\exception\runtime_exception $e)
+			{
+				$io->writeError([[$e->getMessage(), $e->get_parameters(), 4]], true);
+			}
+			catch (\Exception $e)
+			{
+				$io->writeError([[$e->getMessage(), [], 4]], true);
+			}
+		}
+	}
+
+	/**
+	 * {@inheritdoc}
+	 */
+	public function remove(array $packages, IOInterface $io = null)
+	{
+		$packages = $this->normalize_version($packages);
+
+		$not_installed = array_diff(array_keys($packages), array_keys($this->extension_manager->all_available()));
+		if (count($not_installed) !== 0)
+		{
+			throw new runtime_exception($this->exception_prefix, 'NOT_INSTALLED', [implode('|', array_keys($not_installed))]);
+		}
+
+		parent::remove($packages, $io);
+	}
+
+	/**
+	 * {@inheritdoc}
+	 */
+	public function pre_remove(array $packages, IOInterface $io = null)
+	{
+		if ($this->purge_on_remove)
+		{
+			$io->writeError([['DISABLING_EXTENSIONS', [], 1]], true);
+		}
+
+		foreach ($packages as $package => $version)
+		{
+			try
+			{
+				if ($this->extension_manager->is_enabled($package))
+				{
+					if ($this->purge_on_remove)
+					{
+						$this->extension_manager->purge($package);
+					}
+					else
+					{
+						$this->extension_manager->disable($package);
+					}
+				}
+			}
+			catch (\phpbb\exception\runtime_exception $e)
+			{
+				$io->writeError([[$e->getMessage(), $e->get_parameters(), 4]], true);
+			}
+			catch (\Exception $e)
+			{
+				$io->writeError([[$e->getMessage(), [], 4]], true);
+			}
+		}
+	}
+
+	/**
+	 * {@inheritdoc}
+	 */
+	public function start_managing($package, $io)
+	{
+		if (!$this->extension_manager->is_available($package))
+		{
+			throw new runtime_exception($this->exception_prefix, 'NOT_INSTALLED', [$package]);
+		}
+
+		if ($this->is_managed($package))
+		{
+			throw new runtime_exception($this->exception_prefix, 'ALREADY_MANAGED', [$package]);
+		}
+
+		$enabled = false;
+		if ($this->extension_manager->is_enabled($package))
+		{
+			$enabled = true;
+			$io->writeError([['DISABLING_EXTENSIONS', [], 1]], true);
+			$this->extension_manager->disable($package);
+		}
+
+		$ext_path = $this->extension_manager->get_extension_path($package, true);
+		$backup_path = rtrim($ext_path, '/') . '__backup__';
+
+		try
+		{
+			$this->filesystem->rename($ext_path, $backup_path);
+		}
+		catch (filesystem_exception $e)
+		{
+			throw new runtime_exception($this->exception_prefix, 'CANNOT_MANAGE_FILESYSTEM_ERROR', [$package], $e);
+		}
+
+		try
+		{
+			$this->install((array) $package, $io);
+			$this->filesystem->remove($backup_path);
+		}
+		catch (runtime_exception $e)
+		{
+			$this->filesystem->rename($backup_path, $ext_path);
+			throw new runtime_exception($this->exception_prefix, 'CANNOT_MANAGE_INSTALL_ERROR', [$package], $e);
+		}
+		catch (filesystem_exception $e)
+		{
+			throw new managed_with_clean_error_exception($this->exception_prefix, 'MANAGED_WITH_CLEAN_ERROR', [$package, $backup_path], $e);
+		}
+
+		if ($enabled)
+		{
+			try
+			{
+				$io->writeError([['ENABLING_EXTENSIONS', [], 1]], true);
+				$this->extension_manager->enable($package);
+			}
+			catch (\Exception $e)
+			{
+				throw new managed_with_enable_error_exception($this->exception_prefix, 'MANAGED_WITH_ENABLE_ERROR', [$package], $e);
+			}
+		}
+	}
+
+	/**
+	 * {@inheritdoc}
+	 */
+	public function check_requirements()
+	{
+		return parent::check_requirements() && $this->filesystem->is_writable($this->root_path . 'ext/');
+	}
+
+	/**
+	 * Enable the extensions when installing
+	 *
+	 * Warning: Only the explicitly required extensions will be enabled
+	 *
+	 * @param bool $enable
+	 */
+	public function set_enable_on_install($enable)
+	{
+		$this->enable_on_install = $enable;
+	}
+
+	/**
+	 * Purge the extension when disabling it
+	 *
+	 * @param bool $purge
+	 */
+	public function set_purge_on_remove($purge)
+	{
+		$this->purge_on_remove = $purge;
+	}
+}
diff --git a/phpBB/phpbb/composer/installer.php b/phpBB/phpbb/composer/installer.php
new file mode 100644
index 0000000000..6de57541fb
--- /dev/null
+++ b/phpBB/phpbb/composer/installer.php
@@ -0,0 +1,710 @@
+<?php
+/**
+ *
+ * This file is part of the phpBB Forum Software package.
+ *
+ * @copyright (c) phpBB Limited <https://www.phpbb.com>
+ * @license GNU General Public License, version 2 (GPL-2.0)
+ *
+ * For full copyright and license information, please see
+ * the docs/CREDITS.txt file.
+ *
+ */
+
+namespace phpbb\composer;
+
+use Composer\Composer;
+use Composer\Factory;
+use Composer\IO\IOInterface;
+use Composer\IO\NullIO;
+use Composer\Json\JsonFile;
+use Composer\Package\BasePackage;
+use Composer\Package\CompletePackage;
+use Composer\Repository\ComposerRepository;
+use Composer\Semver\Constraint\ConstraintInterface;
+use Composer\Util\RemoteFilesystem;
+use phpbb\composer\io\null_io;
+use phpbb\config\config;
+use phpbb\exception\runtime_exception;
+use phpbb\filesystem\filesystem;
+use phpbb\request\request;
+use Seld\JsonLint\ParsingException;
+
+/**
+ * Class to install packages through composer while freezing core dependencies.
+ */
+class installer
+{
+	const PHPBB_TYPES = 'phpbb-extension,phpbb-style,phpbb-language';
+
+	/**
+	 * @var array Repositories to look packages from
+	 */
+	protected $repositories = [];
+
+	/**
+	 * @var bool Indicates whether packagist usage is allowed or not
+	 */
+	protected $packagist = false;
+
+	/**
+	 * @var string Composer filename used to manage the packages
+	 */
+	protected $composer_filename = 'composer-ext.json';
+
+	/**
+	 * @var string Directory where to install packages vendors
+	 */
+	protected $packages_vendor_dir = 'vendor-ext/';
+
+	/**
+	 * @var string Minimum stability
+	 */
+	protected $minimum_stability = 'stable';
+
+	/**
+	 * @var string phpBB root path
+	 */
+	protected $root_path;
+
+	/**
+	 * @var string Stores the original working directory in case it has been changed through move_to_root()
+	 */
+	private $original_cwd;
+
+	/**
+	 * @var array Stores the content of the ext json file before generate_ext_json_file() overrides it
+	 */
+	private $ext_json_file_backup;
+
+	/**
+	 * @var request phpBB request object
+	 */
+	private $request;
+
+	/**
+	 * @param string		$root_path	phpBB root path
+	 * @param filesystem	$filesystem	Filesystem object
+	 * @param request		$request	phpBB request object
+	 * @param config		$config		Config object
+	 */
+	public function __construct($root_path, filesystem $filesystem, request $request, config $config = null)
+	{
+		if ($config)
+		{
+			$repositories = json_decode($config['exts_composer_repositories'], true);
+
+			if (is_array($repositories) && !empty($repositories))
+			{
+				$this->repositories = (array) $repositories;
+			}
+
+			$this->packagist			= (bool) $config['exts_composer_packagist'];
+			$this->composer_filename	= $config['exts_composer_json_file'];
+			$this->packages_vendor_dir	= $config['exts_composer_vendor_dir'];
+			$this->minimum_stability	= $config['exts_composer_minimum_stability'];
+		}
+
+		$this->root_path = $root_path;
+		$this->request = $request;
+
+		putenv('COMPOSER_HOME=' . $filesystem->realpath($root_path) . '/store/composer');
+	}
+
+	/**
+	 * Update the current installed set of packages
+	 *
+	 * @param array $packages Packages to install.
+	 *        Each entry may be a name or an array associating a version constraint to a name
+	 * @param array $whitelist White-listed packages (packages that can be installed/updated/removed)
+	 * @param IOInterface $io IO object used for the output
+	 *
+	 * @throws runtime_exception
+	 */
+	public function install(array $packages, $whitelist, IOInterface $io = null)
+	{
+		$this->wrap(function() use ($packages, $whitelist, $io) {
+			$this->do_install($packages, $whitelist, $io);
+		});
+	}
+
+	/**
+	 * Update the current installed set of packages
+	 *
+	 * /!\ Doesn't change the current working directory
+	 *
+	 * @param array $packages Packages to install.
+	 *        Each entry may be a name or an array associating a version constraint to a name
+	 * @param array $whitelist White-listed packages (packages that can be installed/updated/removed)
+	 * @param IOInterface $io IO object used for the output
+	 *
+	 * @throws runtime_exception
+	 */
+	protected function do_install(array $packages, $whitelist, IOInterface $io = null)
+	{
+		if (!$io)
+		{
+			$io = new null_io();
+		}
+
+		$this->generate_ext_json_file($packages);
+
+		$composer = Factory::create($io, $this->get_composer_ext_json_filename(), false);
+		$install = \Composer\Installer::create($io, $composer);
+
+		$composer->getDownloadManager()->setOutputProgress(false);
+
+		$install
+			->setVerbose(true)
+			->setPreferSource(false)
+			->setPreferDist(true)
+			->setDevMode(false)
+			->setUpdate(true)
+			->setUpdateWhitelist($whitelist)
+			->setWhitelistDependencies(false)
+			->setIgnorePlatformRequirements(false)
+			->setOptimizeAutoloader(true)
+			->setDumpAutoloader(true)
+			->setPreferStable(true)
+			->setRunScripts(false)
+			->setDryRun(false);
+
+		try
+		{
+			$result = $install->run();
+		}
+		catch (\Exception $e)
+		{
+			$this->restore_ext_json_file();
+
+			throw new runtime_exception('COMPOSER_CANNOT_INSTALL', [], $e);
+		}
+
+		if ($result !== 0)
+		{
+			$this->restore_ext_json_file();
+
+			throw new runtime_exception($io->get_composer_error(), []);
+		}
+	}
+
+	/**
+	 * Returns the list of currently installed packages
+	 *
+	 * @param string|array $types Returns only the packages with the given type(s)
+	 *
+	 * @return array The installed packages associated to their version.
+	 *
+	 * @throws runtime_exception
+	 */
+	public function get_installed_packages($types)
+	{
+		return $this->wrap(function() use ($types) {
+			return $this->do_get_installed_packages($types);
+		});
+	}
+
+	/**
+	 * Returns the list of currently installed packages
+	 *
+	 * /!\ Doesn't change the current working directory
+	 *
+	 * @param string|array $types Returns only the packages with the given type(s)
+	 *
+	 * @return array The installed packages associated to their version.
+	 */
+	protected function do_get_installed_packages($types)
+	{
+		$types = (array) $types;
+
+		try
+		{
+			$io = new NullIO();
+			$composer = Factory::create($io, $this->get_composer_ext_json_filename(), false);
+
+			$installed = [];
+
+			/** @var \Composer\Package\Link[] $required_links */
+			$required_links = $composer->getPackage()->getRequires();
+			$installed_packages = $composer->getRepositoryManager()->getLocalRepository()->getCanonicalPackages();
+
+			foreach ($installed_packages as $package)
+			{
+				if (in_array($package->getType(), $types, true))
+				{
+					$version = array_key_exists($package->getName(), $required_links) ?
+						$required_links[$package->getName()]->getPrettyConstraint() : '*';
+					$installed[$package->getName()] = $version;
+				}
+			}
+
+			return $installed;
+		}
+		catch (\Exception $e)
+		{
+			return [];
+		}
+	}
+
+	/**
+	 * Gets the list of the available packages of the configured type in the configured repositories
+	 *
+	 * /!\ Doesn't change the current working directory
+	 *
+	 * @param string $type Returns only the packages with the given type
+	 *
+	 * @return array The name of the available packages, associated to their definition. Ordered by name.
+	 *
+	 * @throws runtime_exception
+	 */
+	public function get_available_packages($type)
+	{
+		return $this->wrap(function() use ($type) {
+			return $this->do_get_available_packages($type);
+		});
+	}
+
+	/**
+	 * Gets the list of the available packages of the configured type in the configured repositories
+	 *
+	 * @param string $type Returns only the packages with the given type
+	 *
+	 * @return array The name of the available packages, associated to their definition. Ordered by name.
+	 */
+	protected function do_get_available_packages($type)
+	{
+		try
+		{
+			$this->generate_ext_json_file($this->do_get_installed_packages(explode(',', self::PHPBB_TYPES)));
+
+			$io = new NullIO();
+			$composer = Factory::create($io, $this->get_composer_ext_json_filename(), false);
+
+			/** @var ConstraintInterface $core_constraint */
+			$core_constraint = $composer->getPackage()->getRequires()['phpbb/phpbb']->getConstraint();
+			$core_stability = $composer->getPackage()->getMinimumStability();
+
+			$available = [];
+
+			$compatible_packages = [];
+			$repositories = $composer->getRepositoryManager()->getRepositories();
+
+			/** @var \Composer\Repository\RepositoryInterface $repository */
+			foreach ($repositories as $repository)
+			{
+				try
+				{
+					if ($repository instanceof ComposerRepository && $repository->hasProviders())
+					{
+						// Special case for packagist which exposes an api to retrieve all packages of a given type.
+						// For the others composer repositories with providers we can't do anything. It would be too slow.
+
+						$r        = new \ReflectionObject($repository);
+						$repo_url = $r->getProperty('url');
+						$repo_url->setAccessible(true);
+
+						if ($repo_url->getValue($repository) === 'http://packagist.org')
+						{
+							$url      = 'https://packagist.org/packages/list.json?type=' . $type;
+							$rfs      = new RemoteFilesystem($io);
+							$hostname = parse_url($url, PHP_URL_HOST) ?: $url;
+							$json     = $rfs->getContents($hostname, $url, false);
+
+							/** @var \Composer\Package\PackageInterface $package */
+							foreach (JsonFile::parseJson($json, $url)['packageNames'] as $package)
+							{
+								$versions            = $repository->findPackages($package);
+								$compatible_packages = $this->get_compatible_versions($compatible_packages, $core_constraint, $core_stability, $package, $versions);
+							}
+						}
+					}
+					else
+					{
+						// Pre-filter repo packages by their type
+						$packages = [];
+						/** @var \Composer\Package\PackageInterface $package */
+						foreach ($repository->getPackages() as $package)
+						{
+							if ($package->getType() === $type)
+							{
+								$packages[$package->getName()][] = $package;
+							}
+						}
+
+						// Filter the compatibles versions
+						foreach ($packages as $package => $versions)
+						{
+							$compatible_packages = $this->get_compatible_versions($compatible_packages, $core_constraint, $core_stability, $package, $versions);
+						}
+					}
+				}
+				catch (\Exception $e)
+				{
+					// If a repo fails, just skip it.
+					continue;
+				}
+			}
+
+			foreach ($compatible_packages as $name => $versions)
+			{
+				// Determine the highest version of the package
+				/** @var CompletePackage $highest_version */
+				$highest_version = null;
+
+				/** @var CompletePackage $version */
+				foreach ($versions as $version)
+				{
+					if (!$highest_version || version_compare($version->getVersion(), $highest_version->getVersion(), '>'))
+					{
+						$highest_version = $version;
+					}
+				}
+
+				// Generates the entry
+				$available[$name] = [];
+				$available[$name]['name'] = $highest_version->getPrettyName();
+				$available[$name]['display_name'] = $highest_version->getExtra()['display-name'];
+				$available[$name]['composer_name'] = $highest_version->getName();
+				$available[$name]['version'] = $highest_version->getPrettyVersion();
+
+				if ($version instanceof CompletePackage)
+				{
+					$available[$name]['description'] = $highest_version->getDescription();
+					$available[$name]['url'] = $highest_version->getHomepage();
+					$available[$name]['authors'] = $highest_version->getAuthors();
+				}
+				else
+				{
+					$available[$name]['description'] = '';
+					$available[$name]['url'] = '';
+					$available[$name]['authors'] = [];
+				}
+			}
+
+			usort($available, function($a, $b)
+			{
+				return strcasecmp($a['display_name'], $b['display_name']);
+			});
+
+			return $available;
+		}
+		catch (\Exception $e)
+		{
+			return [];
+		}
+	}
+
+	/**
+	 * Checks the requirements of the manager and returns true if it can be used.
+	 *
+	 * @return bool
+	 */
+	public function check_requirements()
+	{
+		$filesystem = new \phpbb\filesystem\filesystem();
+
+		return $filesystem->is_writable([
+			$this->root_path . $this->composer_filename,
+			$this->root_path . $this->packages_vendor_dir,
+			$this->root_path . substr($this->composer_filename, 0, -5) . '.lock',
+		]);
+	}
+
+	/**
+	 * Updates $compatible_packages with the versions of $versions compatibles with the $core_constraint
+	 *
+	 * @param array						$compatible_packages	List of compatibles versions
+	 * @param ConstraintInterface	$core_constraint		Constraint against the phpBB version
+	 * @param string $core_stability Core stability
+	 * @param string					$package_name			Considered package
+	 * @param array						$versions				List of available versions
+	 *
+	 * @return array
+	 */
+	private function get_compatible_versions(array $compatible_packages, ConstraintInterface $core_constraint, $core_stability, $package_name, array $versions)
+	{
+		$core_stability_value = BasePackage::$stabilities[$core_stability];
+
+		/** @var \Composer\Package\PackageInterface $version */
+		foreach ($versions as $version)
+		{
+			try
+			{
+				if (BasePackage::$stabilities[$version->getStability()] > $core_stability_value)
+				{
+					continue;
+				}
+
+				if (array_key_exists('phpbb/phpbb', $version->getRequires()))
+				{
+					/** @var ConstraintInterface $package_constraint */
+					$package_constraint = $version->getRequires()['phpbb/phpbb']->getConstraint();
+
+					if (!$package_constraint->matches($core_constraint))
+					{
+						continue;
+					}
+				}
+
+				$compatible_packages[$package_name][] = $version;
+			}
+			catch (\Exception $e)
+			{
+				// Do nothing (to log when a true debug logger is available)
+			}
+		}
+
+		return $compatible_packages;
+	}
+
+	/**
+	 * Generates and write the json file used to install the set of packages
+	 *
+	 * @param array $packages Packages to update.
+	 *        Each entry may be a name or an array associating a version constraint to a name
+	 */
+	protected function generate_ext_json_file(array $packages)
+	{
+		$io = new NullIO();
+
+		$composer = Factory::create($io, null, false);
+
+		$core_packages = $this->get_core_packages($composer);
+		$ext_json_data = [
+			'require' => array_merge(
+				['php' => $this->get_core_php_requirement($composer)],
+				$core_packages,
+				$this->get_extra_dependencies(),
+				$packages),
+			'replace' => $core_packages,
+			'repositories' => $this->get_composer_repositories(),
+			'config' => [
+				'vendor-dir'=> $this->packages_vendor_dir,
+			],
+			'minimum-stability' => $this->minimum_stability,
+		];
+
+		$this->ext_json_file_backup = null;
+		$json_file = new JsonFile($this->get_composer_ext_json_filename());
+
+		try
+		{
+			$ext_json_file_backup = $json_file->read();
+		}
+		catch (ParsingException $e)
+		{
+			$ext_json_file_backup = '{}';
+
+			$lockFile = new JsonFile(substr($this->get_composer_ext_json_filename(), 0, -5) . '.lock');
+			$lockFile->write([]);
+		}
+
+		$json_file->write($ext_json_data);
+		$this->ext_json_file_backup = $ext_json_file_backup;
+	}
+
+	/**
+	 * Restore the json file overridden by generate_ext_json_file()
+	 */
+	protected function restore_ext_json_file()
+	{
+		if ($this->ext_json_file_backup)
+		{
+			try
+			{
+				$json_file = new JsonFile($this->get_composer_ext_json_filename());
+				$json_file->write($this->ext_json_file_backup);
+			}
+			catch (\Exception $e)
+			{
+			}
+
+			$this->ext_json_file_backup = null;
+		}
+	}
+
+	/**
+	 * Get the core installed packages
+	 *
+	 * @param Composer $composer Composer object to load the dependencies
+	 * @return array The core packages with their version
+	 */
+	protected function get_core_packages(Composer $composer)
+	{
+		$core_deps = [];
+		$packages = $composer->getRepositoryManager()->getLocalRepository()->getCanonicalPackages();
+
+		foreach ($packages as $package)
+		{
+			$core_deps[$package->getName()] = $package->getPrettyVersion();
+		}
+
+		$core_deps['phpbb/phpbb'] = PHPBB_VERSION;
+
+		return $core_deps;
+	}
+
+	/**
+	 * Get the PHP version required by the core
+	 *
+	 * @param Composer $composer Composer object to load the dependencies
+	 * @return string The PHP version required by the core
+	 */
+	protected function get_core_php_requirement(Composer $composer)
+	{
+		return $composer->getLocker()->getLockData()['platform']['php'];
+	}
+
+	/**
+	 * Generate the repositories entry of the packages json file
+	 *
+	 * @return array repositories entry
+	 */
+	protected function get_composer_repositories()
+	{
+		$repositories = [];
+
+		if (!$this->packagist)
+		{
+			$repositories[]['packagist'] = false;
+		}
+
+		foreach ($this->repositories as $repository)
+		{
+			if (preg_match('#^' . get_preg_expression('url') . '$#iu', $repository))
+			{
+				$repositories[] = [
+					'type' => 'composer',
+					'url' => $repository,
+				];
+			}
+		}
+
+		return $repositories;
+	}
+
+	/**
+	 * Get the name of the json file used for the packages.
+	 *
+	 * @return string The json filename
+	 */
+	protected function get_composer_ext_json_filename()
+	{
+		return $this->composer_filename;
+	}
+
+	/**
+	 * Get extra dependencies required to install the packages
+	 *
+	 * @return array Array of composer dependencies
+	 */
+	protected function get_extra_dependencies()
+	{
+		return [];
+	}
+
+	/**
+	 * Sets the customs repositories
+	 *
+	 * @param array $repositories An array of composer repositories to use
+	 */
+	public function set_repositories(array $repositories)
+	{
+		$this->repositories = $repositories;
+	}
+
+	/**
+	 * Allow or disallow packagist
+	 *
+	 * @param boolean $packagist
+	 */
+	public function set_packagist($packagist)
+	{
+		$this->packagist = $packagist;
+	}
+
+	/**
+	 * Sets the name of the managed packages' json file
+	 *
+	 * @param string $composer_filename
+	 */
+	public function set_composer_filename($composer_filename)
+	{
+		$this->composer_filename = $composer_filename;
+	}
+
+	/**
+	 * Sets the location of the managed packages' vendors
+	 *
+	 * @param string $packages_vendor_dir
+	 */
+	public function set_packages_vendor_dir($packages_vendor_dir)
+	{
+		$this->packages_vendor_dir = $packages_vendor_dir;
+	}
+
+	/**
+	 * Sets the phpBB root path
+	 *
+	 * @param string $root_path
+	 */
+	public function set_root_path($root_path)
+	{
+		$this->root_path = $root_path;
+	}
+
+	/**
+	 * Change the current directory to phpBB root
+	 */
+	protected function move_to_root()
+	{
+		if ($this->original_cwd === null)
+		{
+			$this->original_cwd = getcwd();
+			chdir($this->root_path);
+		}
+	}
+
+	/**
+	 * Restore the current working directory if move_to_root() have been called
+	 */
+	protected function restore_cwd()
+	{
+		if ($this->original_cwd)
+		{
+			chdir($this->original_cwd);
+			$this->original_cwd = null;
+		}
+	}
+
+	/**
+	 * Wraps a callable in order to adjust the context needed by composer
+	 *
+	 * @param callable $callable
+	 *
+	 * @return mixed
+	 */
+	protected function wrap(callable $callable)
+	{
+		// The composer installers works with a path relative to the current directory
+		$this->move_to_root();
+
+		// The composer installers uses some super globals
+		$super_globals = $this->request->super_globals_disabled();
+		$this->request->enable_super_globals();
+
+		try
+		{
+			return $callable();
+		}
+		finally
+		{
+			$this->restore_cwd();
+
+			if ($super_globals)
+			{
+				$this->request->disable_super_globals();
+			}
+		}
+	}
+}
diff --git a/phpBB/phpbb/composer/io/console_io.php b/phpBB/phpbb/composer/io/console_io.php
new file mode 100644
index 0000000000..5239b050bb
--- /dev/null
+++ b/phpBB/phpbb/composer/io/console_io.php
@@ -0,0 +1,40 @@
+<?php
+/**
+ *
+ * This file is part of the phpBB Forum Software package.
+ *
+ * @copyright (c) phpBB Limited <https://www.phpbb.com>
+ * @license GNU General Public License, version 2 (GPL-2.0)
+ *
+ * For full copyright and license information, please see
+ * the docs/CREDITS.txt file.
+ *
+ */
+
+namespace phpbb\composer\io;
+
+use Composer\IO\ConsoleIO;
+use phpbb\language\language;
+use Symfony\Component\Console\Helper\HelperSet;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Output\OutputInterface;
+
+class console_io extends ConsoleIO implements io_interface
+{
+	use translate_composer_trait;
+
+	/**
+	 * Constructor.
+	 *
+	 * @param InputInterface	$input		The input instance
+	 * @param OutputInterface	$output		The output instance
+	 * @param HelperSet			$helperSet	The helperSet instance
+	 * @param language			$language	Language object
+	 */
+	public function __construct(InputInterface $input, OutputInterface $output, HelperSet $helperSet, language $language)
+	{
+		$this->language = $language;
+
+		parent::__construct($input, $output, $helperSet);
+	}
+}
diff --git a/phpBB/phpbb/composer/io/html_output_formatter.php b/phpBB/phpbb/composer/io/html_output_formatter.php
new file mode 100644
index 0000000000..588be30a21
--- /dev/null
+++ b/phpBB/phpbb/composer/io/html_output_formatter.php
@@ -0,0 +1,86 @@
+<?php
+/**
+ *
+ * This file is part of the phpBB Forum Software package.
+ *
+ * @copyright (c) phpBB Limited <https://www.phpbb.com>
+ * @license       GNU General Public License, version 2 (GPL-2.0)
+ *
+ * For full copyright and license information, please see
+ * the docs/CREDITS.txt file.
+ *
+ */
+
+namespace phpbb\composer\io;
+
+class html_output_formatter extends \Composer\Console\HtmlOutputFormatter
+{
+	protected static $availableForegroundColors = [
+			30 => 'black',
+			31 => 'red',
+			32 => 'green',
+			33 => 'orange',
+			34 => 'blue',
+			35 => 'magenta',
+			36 => 'cyan',
+			37 => 'white',
+		];
+
+	protected static $availableBackgroundColors = [
+			40 => 'black',
+			41 => 'red',
+			42 => 'green',
+			43 => 'yellow',
+			44 => 'blue',
+			45 => 'magenta',
+			46 => 'cyan',
+			47 => 'white',
+		];
+
+	protected static $availableOptions
+		= [
+			1 => 'bold',
+			4 => 'underscore',
+		];
+
+	/**
+	 * {@inheritdoc}
+	 */
+	public function format($message)
+	{
+		$formatted = parent::format($message);
+
+		return preg_replace_callback("{[\033\e]\[([0-9;]+)m(.*?)[\033\e]\[[0-9;]+m}s", [$this, 'formatHtml'], $formatted);
+	}
+
+	protected function formatHtml($matches)
+	{
+		$out = '<span style="';
+		foreach (explode(';', $matches[1]) as $code)
+		{
+			if (isset(self::$availableForegroundColors[$code]))
+			{
+				$out .= 'color:' . self::$availableForegroundColors[$code] . ';';
+			}
+			else if (isset(self::$availableBackgroundColors[$code]))
+			{
+				$out .= 'background-color:' . self::$availableBackgroundColors[$code] . ';';
+			}
+			else if (isset(self::$availableOptions[$code]))
+			{
+				switch (self::$availableOptions[$code])
+				{
+					case 'bold':
+						$out .= 'font-weight:bold;';
+						break;
+
+					case 'underscore':
+						$out .= 'text-decoration:underline;';
+						break;
+				}
+			}
+		}
+
+		return $out . '">' . $matches[2] . '</span>';
+	}
+}
diff --git a/phpBB/phpbb/composer/io/io_interface.php b/phpBB/phpbb/composer/io/io_interface.php
new file mode 100644
index 0000000000..a1d41122cb
--- /dev/null
+++ b/phpBB/phpbb/composer/io/io_interface.php
@@ -0,0 +1,26 @@
+<?php
+/**
+ *
+ * This file is part of the phpBB Forum Software package.
+ *
+ * @copyright (c) phpBB Limited <https://www.phpbb.com>
+ * @license GNU General Public License, version 2 (GPL-2.0)
+ *
+ * For full copyright and license information, please see
+ * the docs/CREDITS.txt file.
+ *
+ */
+
+namespace phpbb\composer\io;
+
+use Composer\IO\IOInterface;
+
+interface io_interface extends IOInterface
+{
+	/**
+	 * Returns the composer errors that occurred since the last tcall of the method.
+	 *
+	 * @return string
+	 */
+	public function get_composer_error();
+}
diff --git a/phpBB/phpbb/composer/io/null_io.php b/phpBB/phpbb/composer/io/null_io.php
new file mode 100644
index 0000000000..9a667ca097
--- /dev/null
+++ b/phpBB/phpbb/composer/io/null_io.php
@@ -0,0 +1,27 @@
+<?php
+/**
+ *
+ * This file is part of the phpBB Forum Software package.
+ *
+ * @copyright (c) phpBB Limited <https://www.phpbb.com>
+ * @license GNU General Public License, version 2 (GPL-2.0)
+ *
+ * For full copyright and license information, please see
+ * the docs/CREDITS.txt file.
+ *
+ */
+
+namespace phpbb\composer\io;
+
+use Composer\IO\NullIO;
+
+class null_io extends NullIO implements io_interface
+{
+	/**
+	 * {@inheritdoc}
+	 */
+	public function get_composer_error()
+	{
+		return '';
+	}
+}
diff --git a/phpBB/phpbb/composer/io/translate_composer_trait.php b/phpBB/phpbb/composer/io/translate_composer_trait.php
new file mode 100644
index 0000000000..444cf38e6b
--- /dev/null
+++ b/phpBB/phpbb/composer/io/translate_composer_trait.php
@@ -0,0 +1,245 @@
+<?php
+/**
+ *
+ * This file is part of the phpBB Forum Software package.
+ *
+ * @copyright (c) phpBB Limited <https://www.phpbb.com>
+ * @license GNU General Public License, version 2 (GPL-2.0)
+ *
+ * For full copyright and license information, please see
+ * the docs/CREDITS.txt file.
+ *
+ */
+
+namespace phpbb\composer\io;
+
+use Symfony\Component\Console\Output\OutputInterface;
+
+/**
+ * Trait to translate the composer Output
+ */
+trait translate_composer_trait
+{
+	/**
+	 * @var \phpbb\language\language
+	 */
+	protected $language;
+
+	/**
+	 * @var array
+	 */
+	protected $composer_error = [];
+
+	/**
+	 * {@inheritdoc}
+	 */
+	public function write($messages, $newline = true, $verbosity = self::NORMAL)
+	{
+		$messages = (array) $messages;
+		$translated_messages = [];
+
+		foreach ($messages as $message)
+		{
+			$level = 0;
+			if (is_array($message))
+			{
+				$lang_key = $message[0];
+				$parameters = $message[1];
+				if (count($message) > 2)
+				{
+					$level = $message[2];
+				}
+			}
+			else
+			{
+				$lang_key = $message;
+				$parameters = [];
+			}
+
+			$message = trim($this->strip_format($lang_key), "\n\r");
+
+			if ($this->output->getVerbosity() === OutputInterface::VERBOSITY_DEBUG)
+			{
+				// Do nothing
+			}
+			else if (strpos($message, 'Deleting ') === 0)
+			{
+				$elements = explode(' ', $message);
+				$lang_key = 'COMPOSER_DELETING';
+				$parameters = [$elements[1]];
+			}
+
+			$translated_message = $this->language->lang_array($lang_key, $parameters);
+
+			switch ($level)
+			{
+				case 1:
+					$translated_message = '<info>' . $translated_message . '</info>';
+					break;
+				case 2:
+					$translated_message = '<comment>' . $translated_message . '</comment>';
+					break;
+				case 3:
+					$translated_message = '<warning>' . $translated_message . '</warning>';
+					break;
+				case 4:
+					$translated_message = '<error>' . $translated_message . '</error>';
+					break;
+			}
+
+			$translated_messages[] = $translated_message;
+		}
+
+		parent::write($translated_messages, $newline);
+	}
+
+	/**
+	 * {@inheritdoc}
+	 */
+	public function writeError($messages, $newline = true, $verbosity = self::NORMAL)
+	{
+		$messages = (array) $messages;
+		$translated_messages = [];
+
+		foreach ($messages as $message)
+		{
+			$level = 0;
+			if (is_array($message))
+			{
+				$lang_key = $message[0];
+				$parameters = $message[1];
+				if (count($message) > 2)
+				{
+					$level = $message[2];
+				}
+			}
+			else
+			{
+				$lang_key = $message;
+				$parameters = [];
+			}
+
+			$message = trim($this->strip_format($lang_key), "\n\r");
+
+			if ($message === 'Your requirements could not be resolved to an installable set of packages.')
+			{
+				$this->composer_error[] = ['COMPOSER_ERROR_CONFLICT', []];
+
+				if ($this->output->getVerbosity() < OutputInterface::VERBOSITY_DEBUG)
+				{
+					continue;
+				}
+			}
+			else if (strpos($message, '  Problem ') === 0)
+			{
+				if ($this->output->getVerbosity() < OutputInterface::VERBOSITY_VERBOSE)
+				{
+					continue;
+				}
+
+				$lang_key = "\n" . htmlentities($message) . "\n";
+				$level = 4;
+			}
+			else if ($message === 'Updating dependencies')
+			{
+				$lang_key = 'COMPOSER_UPDATING_DEPENDENCIES';
+				$level = 1;
+			}
+			else if ($message === 'Loading composer repositories with package information')
+			{
+				$lang_key = 'COMPOSER_LOADING_REPOSITORIES';
+				$level = 1;
+			}
+			else if (strpos($message, 'could not be fully loaded, package information was loaded from the local cache and may be out of date') !== false)
+			{
+				$end_repo = strpos($message, 'could not be fully loaded, package information was loaded from the local cache and may be out of date');
+				$repo = substr($message, 0, $end_repo - 1);
+
+				$lang_key = 'COMPOSER_REPOSITORY_UNAVAILABLE';
+				$parameters = [$repo];
+				$level = 3;
+			}
+			else if (strpos($message, 'file could not be downloaded') !== false)
+			{
+				continue;
+			}
+			else if (strpos($message, '  - Installing ') === 0)
+			{
+				$elements = explode(' ', $message);
+				$lang_key = 'COMPOSER_INSTALLING_PACKAGE';
+				$parameters = [$elements[4], trim($elements[5], '()')];
+			}
+			else if ($message === 'Nothing to install or update')
+			{
+				$lang_key = 'COMPOSER_UPDATE_NOTHING';
+				$level = 3;
+			}
+			else if ($message === '    Downloading')
+			{
+				continue;
+			}
+			else if ($message === '    Loading from cache')
+			{
+				continue;
+			}
+			else if ($message === 'Writing lock file')
+			{
+				continue;
+			}
+			else if ($message === '    Extracting archive')
+			{
+				continue;
+			}
+			else if (empty($message))
+			{
+				continue;
+			}
+
+			$translated_message = $this->language->lang_array($lang_key, $parameters);
+
+			switch ($level)
+			{
+				case 1:
+					$translated_message = '<info>' . $translated_message . '</info>';
+					break;
+				case 2:
+					$translated_message = '<comment>' . $translated_message . '</comment>';
+					break;
+				case 3:
+					$translated_message = '<warning>' . $translated_message . '</warning>';
+					break;
+				case 4:
+					$translated_message = '<error>' . $translated_message . '</error>';
+					break;
+			}
+
+			$translated_messages[] = $translated_message;
+		}
+
+		parent::writeError($translated_messages, $newline);
+	}
+
+	public function get_composer_error()
+	{
+		$error = '';
+		foreach ($this->composer_error as $error_line)
+		{
+			$error .= $this->language->lang_array($error_line[0], $error_line[1]);
+			$error .= "\n";
+		}
+
+		$this->composer_error = [];
+
+		return $error;
+	}
+
+	protected function strip_format($message)
+	{
+		return str_replace([
+			'<info>', '</info>',
+			'<warning>', '</warning>',
+			'<comment>', '</comment>',
+			'<error>', '</error>',
+		], '', $message);
+	}
+}
diff --git a/phpBB/phpbb/composer/io/web_io.php b/phpBB/phpbb/composer/io/web_io.php
new file mode 100644
index 0000000000..4eab3d099a
--- /dev/null
+++ b/phpBB/phpbb/composer/io/web_io.php
@@ -0,0 +1,37 @@
+<?php
+/**
+ *
+ * This file is part of the phpBB Forum Software package.
+ *
+ * @copyright (c) phpBB Limited <https://www.phpbb.com>
+ * @license GNU General Public License, version 2 (GPL-2.0)
+ *
+ * For full copyright and license information, please see
+ * the docs/CREDITS.txt file.
+ *
+ */
+
+namespace phpbb\composer\io;
+
+use Composer\IO\BufferIO;
+use phpbb\language\language;
+use Symfony\Component\Console\Formatter\OutputFormatterInterface;
+use Symfony\Component\Console\Output\StreamOutput;
+
+class web_io extends BufferIO implements io_interface
+{
+	use translate_composer_trait;
+
+	/**
+	 * @param language					$language	Language object
+	 * @param string					$input		Input string
+	 * @param int						$verbosity	Verbosity level
+	 * @param OutputFormatterInterface	$formatter	Output formatter
+	 */
+	public function __construct(language $language, $input = '', $verbosity = StreamOutput::VERBOSITY_NORMAL, OutputFormatterInterface $formatter = null)
+	{
+		$this->language = $language;
+
+		parent::__construct($input, $verbosity, $formatter);
+	}
+}
diff --git a/phpBB/phpbb/composer/manager.php b/phpBB/phpbb/composer/manager.php
new file mode 100644
index 0000000000..43ea8a2503
--- /dev/null
+++ b/phpBB/phpbb/composer/manager.php
@@ -0,0 +1,332 @@
+<?php
+/**
+ *
+ * This file is part of the phpBB Forum Software package.
+ *
+ * @copyright (c) phpBB Limited <https://www.phpbb.com>
+ * @license GNU General Public License, version 2 (GPL-2.0)
+ *
+ * For full copyright and license information, please see
+ * the docs/CREDITS.txt file.
+ *
+ */
+
+namespace phpbb\composer;
+
+use Composer\IO\IOInterface;
+use phpbb\cache\driver\driver_interface;
+use phpbb\composer\exception\runtime_exception;
+
+/**
+ * Class to manage packages through composer.
+ */
+class manager implements manager_interface
+{
+	/**
+	 * @var installer Composer packages installer
+	 */
+	protected $installer;
+
+	/**
+	 * @var driver_interface Cache instance
+	 */
+	protected $cache;
+
+	/**
+	 * @var string Type of packages (phpbb-packages per example)
+	 */
+	protected $package_type;
+
+	/**
+	 * @var string Prefix used for the exception's language string
+	 */
+	protected $exception_prefix;
+
+	/**
+	 * @var array Caches the managed packages list (for the current type)
+	 */
+	private $managed_packages;
+
+	/**
+	 * @var array Caches the managed packages list (for all phpBB types)
+	 */
+	private $all_managed_packages;
+
+	/**
+	 * @var array Caches the available packages list
+	 */
+	private $available_packages;
+
+	/**
+	 * @param installer			$installer			Installer object
+	 * @param driver_interface	$cache				Cache object
+	 * @param string			$package_type		Composer type of managed packages
+	 * @param string			$exception_prefix	Exception prefix to use
+	 */
+	public function __construct(installer $installer, driver_interface $cache, $package_type, $exception_prefix)
+	{
+		$this->installer = $installer;
+		$this->cache = $cache;
+		$this->package_type = $package_type;
+		$this->exception_prefix = $exception_prefix;
+	}
+
+	/**
+	 * {@inheritdoc}
+	 */
+	public function install(array $packages, IOInterface $io = null)
+	{
+		$packages = $this->normalize_version($packages);
+
+		$already_managed = array_intersect(array_keys($this->get_managed_packages()), array_keys($packages));
+		if (count($already_managed) !== 0)
+		{
+			throw new runtime_exception($this->exception_prefix, 'ALREADY_INSTALLED', [implode('|', $already_managed)]);
+		}
+
+		$this->pre_install($packages, $io);
+
+		$managed_packages = array_merge($this->get_all_managed_packages(), $packages);
+		ksort($managed_packages);
+
+		$this->installer->install($managed_packages, array_keys($packages), $io);
+
+		$this->post_install($packages, $io);
+
+		$this->managed_packages = null;
+	}
+
+	/**
+	 * Hook called before installing the packages
+	 *
+	 * @param array $packages Packages to update.
+	 *                        Each entry may be a name or an array associating a version constraint to a name
+	 * @param IOInterface $io IO object used for the output
+	 */
+	protected function pre_install(array $packages, IOInterface $io = null)
+	{
+	}
+
+	/**
+	 * Hook called after installing the packages
+	 *
+	 * @param array $packages Packages to update.
+	 *                        Each entry may be a name or an array associating a version constraint to a name
+	 * @param IOInterface $io IO object used for the output
+	 */
+	protected function post_install(array $packages, IOInterface $io = null)
+	{
+	}
+
+	/**
+	 * {@inheritdoc}
+	 */
+	public function update(array $packages, IOInterface $io = null)
+	{
+		$packages = $this->normalize_version($packages);
+
+		$not_managed = array_diff_key($packages, $this->get_managed_packages());
+		if (count($not_managed) !== 0)
+		{
+			throw new runtime_exception($this->exception_prefix, 'NOT_MANAGED', [implode('|', array_keys($not_managed))]);
+		}
+
+		$this->pre_update($packages, $io);
+
+		$managed_packages = array_merge($this->get_all_managed_packages(), $packages);
+		ksort($managed_packages);
+
+		$this->installer->install($managed_packages, array_keys($packages), $io);
+
+		$this->post_update($packages, $io);
+	}
+
+	/**
+	 * Hook called before updating the packages
+	 *
+	 * @param array $packages Packages to update.
+	 *                        Each entry may be a name or an array associating a version constraint to a name
+	 * @param IOInterface $io IO object used for the output
+	 */
+	protected function pre_update(array $packages, IOInterface $io = null)
+	{
+	}
+
+	/**
+	 * Hook called after updating the packages
+	 *
+	 * @param array $packages Packages to update.
+	 *                        Each entry may be a name or an array associating a version constraint to a name
+	 * @param IOInterface $io IO object used for the output
+	 */
+	protected function post_update(array $packages, IOInterface $io = null)
+	{
+	}
+
+	/**
+	 * {@inheritdoc}
+	 */
+	public function remove(array $packages, IOInterface $io = null)
+	{
+		$packages = $this->normalize_version($packages);
+
+		$not_managed = array_diff_key($packages, $this->get_managed_packages());
+		if (count($not_managed) !== 0)
+		{
+			throw new runtime_exception($this->exception_prefix, 'NOT_MANAGED', [implode('|', array_keys($not_managed))]);
+		}
+
+		$this->pre_remove($packages, $io);
+
+		$managed_packages = array_diff_key($this->get_all_managed_packages(), $packages);
+		ksort($managed_packages);
+
+		$this->installer->install($managed_packages, array_keys($packages), $io);
+
+		$this->post_remove($packages, $io);
+
+		$this->managed_packages = null;
+	}
+
+	/**
+	 * Hook called before removing the packages
+	 *
+	 * @param array $packages Packages to update.
+	 *                        Each entry may be a name or an array associating a version constraint to a name
+	 * @param IOInterface $io IO object used for the output
+	 */
+	protected function pre_remove(array $packages, IOInterface $io = null)
+	{
+	}
+
+	/**
+	 * Hook called after removing the packages
+	 *
+	 * @param array $packages Packages to update.
+	 *                        Each entry may be a name or an array associating a version constraint to a name
+	 * @param IOInterface $io IO object used for the output
+	 */
+	protected function post_remove(array $packages, IOInterface $io = null)
+	{
+	}
+
+	/**
+	 * {@inheritdoc}
+	 */
+	public function is_managed($package)
+	{
+		return array_key_exists($package, $this->get_managed_packages());
+	}
+
+	/**
+	 * {@inheritdoc}
+	 */
+	public function get_managed_packages()
+	{
+		if ($this->managed_packages === null)
+		{
+			$this->managed_packages = $this->installer->get_installed_packages($this->package_type);
+		}
+
+		return $this->managed_packages;
+	}
+
+	/**
+	 * {@inheritdoc}
+	 */
+	public function get_all_managed_packages()
+	{
+		if ($this->all_managed_packages === null)
+		{
+			$this->all_managed_packages = $this->installer->get_installed_packages(explode(',', installer::PHPBB_TYPES));
+		}
+
+		return $this->all_managed_packages;
+	}
+
+	/**
+	 * {@inheritdoc}
+	 */
+	public function get_available_packages()
+	{
+		if ($this->available_packages === null)
+		{
+			$this->available_packages = $this->cache->get('_composer_' . $this->package_type . '_available');
+
+			if (!$this->available_packages)
+			{
+				$this->available_packages = $this->installer->get_available_packages($this->package_type);
+				$this->cache->put('_composer_' . $this->package_type . '_available', $this->available_packages, 24*60*60);
+			}
+		}
+
+		return $this->available_packages;
+	}
+
+	/**
+	 * {@inheritdoc}
+	 */
+	public function reset_cache()
+	{
+		$this->cache->destroy('_composer_' . $this->package_type . '_available');
+
+		$this->available_packages = null;
+		$this->managed_packages = null;
+		$this->all_managed_packages = null;
+	}
+
+	/**
+	 * {@inheritdoc}
+	 */
+	public function start_managing($package, $io)
+	{
+		throw new \phpbb\exception\runtime_exception('COMPOSER_UNSUPPORTED_OPERATION', (array) $this->package_type);
+	}
+
+	/**
+	 * {@inheritdoc}
+	 */
+	public function check_requirements()
+	{
+		return $this->installer->check_requirements();
+	}
+
+	/**
+	 * Normalize a packages/version array. Every entry can have 3 different forms:
+	 *  - $package => $version
+	 *  - $indice => $package:$version
+	 *  - $indice => $package
+	 * They are converted to he form:
+	 *  - $package => $version ($version is set to '*' for the third form)
+	 *
+	 * @param array $packages
+	 *
+	 * @return array
+	 */
+	protected function normalize_version(array $packages)
+	{
+		$normalized_packages = [];
+
+		foreach ($packages as $package => $version)
+		{
+			if (is_numeric($package))
+			{
+				if (strpos($version, ':') !== false)
+				{
+					$parts = explode(':', $version);
+					$normalized_packages[$parts[0]] = $parts[1];
+				}
+				else
+				{
+					$normalized_packages[$version] = '*';
+				}
+			}
+			else
+			{
+				$normalized_packages[$package] = $version;
+			}
+		}
+
+		return $normalized_packages;
+	}
+}
diff --git a/phpBB/phpbb/composer/manager_interface.php b/phpBB/phpbb/composer/manager_interface.php
new file mode 100644
index 0000000000..3cb401f2b6
--- /dev/null
+++ b/phpBB/phpbb/composer/manager_interface.php
@@ -0,0 +1,110 @@
+<?php
+/**
+ *
+ * This file is part of the phpBB Forum Software package.
+ *
+ * @copyright (c) phpBB Limited <https://www.phpbb.com>
+ * @license GNU General Public License, version 2 (GPL-2.0)
+ *
+ * For full copyright and license information, please see
+ * the docs/CREDITS.txt file.
+ *
+ */
+
+namespace phpbb\composer;
+
+use Composer\IO\IOInterface;
+use phpbb\composer\exception\runtime_exception;
+
+/**
+ * Class to manage packages through composer.
+ */
+interface manager_interface
+{
+	/**
+	 * Installs (if necessary) a set of packages
+	 *
+	 * @param array $packages Packages to install.
+	 *                        Each entry may be a name or an array associating a version constraint to a name
+	 * @param IOInterface $io IO object used for the output
+	 *
+	 * @throws runtime_exception
+	 */
+	public function install(array $packages, IOInterface $io = null);
+
+	/**
+	 * Updates or installs a set of packages
+	 *
+	 * @param array $packages Packages to update.
+	 *                        Each entry may be a name or an array associating a version constraint to a name
+	 * @param IOInterface $io IO object used for the output
+	 *
+	 * @throws runtime_exception
+	 */
+	public function update(array $packages, IOInterface $io = null);
+
+	/**
+	 * Removes a set of packages
+	 *
+	 * @param array $packages Packages to remove.
+	 *                        Each entry may be a name or an array associating a version constraint to a name
+	 * @param IOInterface $io IO object used for the output
+	 *
+	 * @throws runtime_exception
+	 */
+	public function remove(array $packages, IOInterface $io = null);
+
+	/**
+	 * Tells whether or not a package is managed by Composer.
+	 *
+	 * @param string $packages Package name
+	 *
+	 * @return bool
+	 */
+	public function is_managed($packages);
+
+	/**
+	 * Returns the list of managed packages for the current type
+	 *
+	 * @return array The managed packages associated to their version.
+	 */
+	public function get_managed_packages();
+
+	/**
+	 * Returns the list of managed packages for all phpBB types
+	 *
+	 * @return array The managed packages associated to their version.
+	 */
+	public function get_all_managed_packages();
+
+	/**
+	 * Returns the list of available packages
+	 *
+	 * @return array The name of the available packages, associated to their definition. Ordered by name.
+	 */
+	public function get_available_packages();
+
+	/**
+	 * Reset the cache
+	 */
+	public function reset_cache();
+
+	/**
+	 * Start managing a manually installed package
+	 *
+	 * Remove a package installed manually and reinstall it using composer.
+	 *
+	 * @param string $package Package to manage
+	 * @param IOInterface $io IO object used for the output
+	 *
+	 * @throws runtime_exception
+	 */
+	public function start_managing($package, $io);
+
+	/**
+	 * Checks the requirements of the manager and returns true if it can be used.
+	 *
+	 * @return bool
+	 */
+	public function check_requirements();
+}
diff --git a/phpBB/phpbb/console/command/extension/install.php b/phpBB/phpbb/console/command/extension/install.php
new file mode 100644
index 0000000000..bbed53be30
--- /dev/null
+++ b/phpBB/phpbb/console/command/extension/install.php
@@ -0,0 +1,103 @@
+<?php
+/**
+*
+* This file is part of the phpBB Forum Software package.
+*
+* @copyright (c) phpBB Limited <https://www.phpbb.com>
+* @license GNU General Public License, version 2 (GPL-2.0)
+*
+* For full copyright and license information, please see
+* the docs/CREDITS.txt file.
+*
+*/
+
+namespace phpbb\console\command\extension;
+
+use phpbb\composer\extension_manager;
+use phpbb\composer\io\console_io;
+use phpbb\language\language;
+use Symfony\Component\Console\Formatter\OutputFormatterStyle;
+use Symfony\Component\Console\Input\InputArgument;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Input\InputOption;
+use Symfony\Component\Console\Output\OutputInterface;
+use Symfony\Component\Console\Style\SymfonyStyle;
+
+class install extends \phpbb\console\command\command
+{
+	/**
+	 * @var extension_manager Composer extensions manager
+	 */
+	protected $manager;
+
+	/**
+	 * @var \phpbb\language\language
+	 */
+	protected $language;
+
+	public function __construct(\phpbb\user $user, extension_manager $manager, language $language)
+	{
+		$this->manager = $manager;
+		$this->language = $language;
+
+		$language->add_lang('acp/extensions');
+
+		parent::__construct($user);
+	}
+
+	/**
+	* Sets the command name and description
+	*
+	* @return null
+	*/
+	protected function configure()
+	{
+		$this
+			->setName('extension:install')
+			->setDescription($this->language->lang('CLI_DESCRIPTION_EXTENSION_INSTALL'))
+			->addOption(
+				'enable',
+				null,
+				InputOption::VALUE_NONE,
+				$this->language->lang('CLI_DESCRIPTION_EXTENSION_INSTALL_OPTION_ENABLE'))
+			->addArgument(
+				'extensions',
+				InputArgument::IS_ARRAY | InputArgument::REQUIRED,
+				$this->language->lang('CLI_DESCRIPTION_EXTENSION_INSTALL_ARGUMENT'))
+		;
+	}
+
+	/**
+	* Executes the command extension:install
+	*
+	* @param InputInterface $input
+	* @param OutputInterface $output
+	* @return integer
+	*/
+	protected function execute(InputInterface $input, OutputInterface $output)
+	{
+		$output->getFormatter()->setStyle('warning', new OutputFormatterStyle('black', 'yellow'));
+
+		$io = new SymfonyStyle($input, $output);
+
+		if (!$this->manager->check_requirements())
+		{
+			$io->error($this->language->lang('EXTENSIONS_COMPOSER_NOT_WRITABLE'));
+			return 1;
+		}
+
+		$composer_io = new console_io($input, $output, $this->getHelperSet(), $this->language);
+		$extensions = $input->getArgument('extensions');
+
+		if ($input->getOption('enable'))
+		{
+			$this->manager->set_enable_on_install(true);
+		}
+
+		$this->manager->install($extensions, $composer_io);
+
+		$io->success($this->language->lang('EXTENSIONS_INSTALLED'));
+
+		return 0;
+	}
+}
diff --git a/phpBB/phpbb/console/command/extension/list_available.php b/phpBB/phpbb/console/command/extension/list_available.php
new file mode 100644
index 0000000000..3d133c9dfa
--- /dev/null
+++ b/phpBB/phpbb/console/command/extension/list_available.php
@@ -0,0 +1,73 @@
+<?php
+/**
+*
+* This file is part of the phpBB Forum Software package.
+*
+* @copyright (c) phpBB Limited <https://www.phpbb.com>
+* @license GNU General Public License, version 2 (GPL-2.0)
+*
+* For full copyright and license information, please see
+* the docs/CREDITS.txt file.
+*
+*/
+
+namespace phpbb\console\command\extension;
+
+use phpbb\composer\manager_interface;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Output\OutputInterface;
+use Symfony\Component\Console\Style\SymfonyStyle;
+
+class list_available extends \phpbb\console\command\command
+{
+	/**
+	 * @var manager_interface Composer extensions manager
+	 */
+	protected $manager;
+
+	public function __construct(\phpbb\user $user, manager_interface $manager)
+	{
+		$this->manager = $manager;
+
+		$user->add_lang('acp/extensions');
+
+		parent::__construct($user);
+	}
+
+	/**
+	* Sets the command name and description
+	*
+	* @return null
+	*/
+	protected function configure()
+	{
+		$this
+			->setName('extension:list-available')
+			->setDescription($this->user->lang('CLI_DESCRIPTION_EXTENSION_LIST_AVAILABLE'))
+		;
+	}
+
+	/**
+	* Executes the command extension:install
+	*
+	* @param InputInterface $input
+	* @param OutputInterface $output
+	* @return integer
+	*/
+	protected function execute(InputInterface $input, OutputInterface $output)
+	{
+		$io = new SymfonyStyle($input, $output);
+
+		$extensions = [];
+
+		foreach ($this->manager->get_available_packages() as $package)
+		{
+			$extensions[] = '<info>' . $package['name'] . '</info> (<comment>' . $package['version'] . '</comment>) ' . $package['url'] .
+			                ($package['description'] ? "\n" . $package['description'] : '');
+		}
+
+		$io->listing($extensions);
+
+		return 0;
+	}
+}
diff --git a/phpBB/phpbb/console/command/extension/manage.php b/phpBB/phpbb/console/command/extension/manage.php
new file mode 100644
index 0000000000..cd8bbc1a7d
--- /dev/null
+++ b/phpBB/phpbb/console/command/extension/manage.php
@@ -0,0 +1,99 @@
+<?php
+/**
+*
+* This file is part of the phpBB Forum Software package.
+*
+* @copyright (c) phpBB Limited <https://www.phpbb.com>
+* @license GNU General Public License, version 2 (GPL-2.0)
+*
+* For full copyright and license information, please see
+* the docs/CREDITS.txt file.
+*
+*/
+
+namespace phpbb\console\command\extension;
+
+use phpbb\composer\exception\managed_with_error_exception;
+use phpbb\composer\io\console_io;
+use phpbb\composer\manager_interface;
+use phpbb\language\language;
+use Symfony\Component\Console\Input\InputArgument;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Output\OutputInterface;
+use Symfony\Component\Console\Style\SymfonyStyle;
+
+class manage extends \phpbb\console\command\command
+{
+	/**
+	 * @var manager_interface Composer extensions manager
+	 */
+	protected $manager;
+
+	/**
+	 * @var \phpbb\language\language
+	 */
+	protected $language;
+
+	public function __construct(\phpbb\user $user, manager_interface $manager, language $language)
+	{
+		$this->manager = $manager;
+		$this->language = $language;
+
+		$language->add_lang('acp/extensions');
+
+		parent::__construct($user);
+	}
+
+	/**
+	* Sets the command name and description
+	*
+	* @return null
+	*/
+	protected function configure()
+	{
+		$this
+			->setName('extension:manage')
+			->setDescription($this->language->lang('CLI_DESCRIPTION_EXTENSION_MANAGE'))
+			->addArgument(
+				'extension',
+				InputArgument::REQUIRED,
+				$this->language->lang('CLI_DESCRIPTION_EXTENSION_MANAGE_ARGUMENT'))
+		;
+	}
+
+	/**
+	* Executes the command extension:install
+	*
+	* @param InputInterface $input
+	* @param OutputInterface $output
+	* @return integer
+	*/
+	protected function execute(InputInterface $input, OutputInterface $output)
+	{
+		$io = new SymfonyStyle($input, $output);
+
+		if (!$this->manager->check_requirements())
+		{
+			$io->error($this->language->lang('EXTENSIONS_COMPOSER_NOT_WRITABLE'));
+			return 1;
+		}
+
+		$composer_io = new console_io($input, $output, $this->getHelperSet(), $this->language);
+
+		$extension = $input->getArgument('extension');
+
+		try
+		{
+			$this->manager->start_managing($extension, $composer_io);
+		}
+		catch (managed_with_error_exception $e)
+		{
+			$io->warning($this->language->lang_array($e->getMessage(), $e->get_parameters()));
+			return 1;
+		}
+
+		$io->success($this->language->lang('EXTENSION_MANAGED_SUCCESS', $extension));
+
+		return 0;
+	}
+}
diff --git a/phpBB/phpbb/console/command/extension/remove.php b/phpBB/phpbb/console/command/extension/remove.php
new file mode 100644
index 0000000000..69d2a62dd9
--- /dev/null
+++ b/phpBB/phpbb/console/command/extension/remove.php
@@ -0,0 +1,103 @@
+<?php
+/**
+*
+* This file is part of the phpBB Forum Software package.
+*
+* @copyright (c) phpBB Limited <https://www.phpbb.com>
+* @license GNU General Public License, version 2 (GPL-2.0)
+*
+* For full copyright and license information, please see
+* the docs/CREDITS.txt file.
+*
+*/
+
+namespace phpbb\console\command\extension;
+
+use phpbb\composer\extension_manager;
+use phpbb\composer\io\console_io;
+use phpbb\language\language;
+use Symfony\Component\Console\Formatter\OutputFormatterStyle;
+use Symfony\Component\Console\Input\InputArgument;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Input\InputOption;
+use Symfony\Component\Console\Output\OutputInterface;
+use Symfony\Component\Console\Style\SymfonyStyle;
+
+class remove extends \phpbb\console\command\command
+{
+	/**
+	 * @var extension_manager Composer extensions manager
+	 */
+	protected $manager;
+
+	/**
+	 * @var \phpbb\language\language
+	 */
+	protected $language;
+
+	public function __construct(\phpbb\user $user, extension_manager $manager, language $language)
+	{
+		$this->manager = $manager;
+		$this->language = $language;
+
+		$language->add_lang('acp/extensions');
+
+		parent::__construct($user);
+	}
+
+	/**
+	* Sets the command name and description
+	*
+	* @return null
+	*/
+	protected function configure()
+	{
+		$this
+			->setName('extension:remove')
+			->setDescription($this->language->lang('CLI_DESCRIPTION_EXTENSION_REMOVE'))
+			->addOption(
+				'purge',
+				null,
+				InputOption::VALUE_NONE,
+				$this->language->lang('CLI_DESCRIPTION_EXTENSION_REMOVE_OPTION_PURGE'))
+			->addArgument(
+				'extensions',
+				InputArgument::IS_ARRAY | InputArgument::REQUIRED,
+				$this->language->lang('CLI_DESCRIPTION_EXTENSION_REMOVE_ARGUMENT'))
+		;
+	}
+
+	/**
+	* Executes the command extension:install
+	*
+	* @param InputInterface $input
+	* @param OutputInterface $output
+	* @return integer
+	*/
+	protected function execute(InputInterface $input, OutputInterface $output)
+	{
+		$output->getFormatter()->setStyle('warning', new OutputFormatterStyle('black', 'yellow'));
+
+		$io = new SymfonyStyle($input, $output);
+
+		if (!$this->manager->check_requirements())
+		{
+			$io->error($this->language->lang('EXTENSIONS_COMPOSER_NOT_WRITABLE'));
+			return 1;
+		}
+
+		$composer_io = new console_io($input, $output, $this->getHelperSet(), $this->language);
+		$extensions = $input->getArgument('extensions');
+
+		if ($input->getOption('purge'))
+		{
+			$this->manager->set_purge_on_remove(true);
+		}
+
+		$this->manager->remove($extensions, $composer_io);
+
+		$io->success($this->language->lang('EXTENSIONS_REMOVED'));
+
+		return 0;
+	}
+}
diff --git a/phpBB/phpbb/console/command/extension/update.php b/phpBB/phpbb/console/command/extension/update.php
new file mode 100644
index 0000000000..f1479c8b0d
--- /dev/null
+++ b/phpBB/phpbb/console/command/extension/update.php
@@ -0,0 +1,90 @@
+<?php
+/**
+*
+* This file is part of the phpBB Forum Software package.
+*
+* @copyright (c) phpBB Limited <https://www.phpbb.com>
+* @license GNU General Public License, version 2 (GPL-2.0)
+*
+* For full copyright and license information, please see
+* the docs/CREDITS.txt file.
+*
+*/
+
+namespace phpbb\console\command\extension;
+
+use phpbb\composer\io\console_io;
+use phpbb\composer\manager_interface;
+use phpbb\language\language;
+use Symfony\Component\Console\Formatter\OutputFormatterStyle;
+use Symfony\Component\Console\Input\InputArgument;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Output\OutputInterface;
+use Symfony\Component\Console\Style\SymfonyStyle;
+
+class update extends \phpbb\console\command\command
+{
+	/**
+	 * @var manager_interface Composer extensions manager
+	 */
+	protected $manager;
+
+	/**
+	 * @var \phpbb\language\language
+	 */
+	protected $language;
+
+	public function __construct(\phpbb\user $user, manager_interface $manager, language $language)
+	{
+		$this->manager = $manager;
+		$this->language = $language;
+
+		parent::__construct($user);
+	}
+
+	/**
+	* Sets the command name and description
+	*
+	* @return null
+	*/
+	protected function configure()
+	{
+		$this
+			->setName('extension:update')
+			->setDescription($this->user->lang('CLI_DESCRIPTION_EXTENSION_UPDATE'))
+			->addArgument(
+				'extensions',
+				InputArgument::IS_ARRAY | InputArgument::REQUIRED,
+				$this->user->lang('CLI_DESCRIPTION_EXTENSION_UPDATE_ARGUMENT'))
+		;
+	}
+
+	/**
+	* Executes the command extension:install
+	*
+	* @param InputInterface $input
+	* @param OutputInterface $output
+	* @return integer
+	*/
+	protected function execute(InputInterface $input, OutputInterface $output)
+	{
+		$output->getFormatter()->setStyle('warning', new OutputFormatterStyle('black', 'yellow'));
+
+		$io = new SymfonyStyle($input, $output);
+
+		if (!$this->manager->check_requirements())
+		{
+			$io->error($this->language->lang('EXTENSIONS_COMPOSER_NOT_WRITABLE'));
+			return 1;
+		}
+
+		$composer_io = new console_io($input, $output, $this->getHelperSet(), $this->language);
+		$extensions = $input->getArgument('extensions');
+
+		$this->manager->update($extensions, $composer_io);
+
+		$io->success($this->language->lang('EXTENSIONS_UPDATED'));
+
+		return 0;
+	}
+}
diff --git a/phpBB/phpbb/db/migration/data/v330/extensions_composer.php b/phpBB/phpbb/db/migration/data/v330/extensions_composer.php
new file mode 100644
index 0000000000..7e12150e56
--- /dev/null
+++ b/phpBB/phpbb/db/migration/data/v330/extensions_composer.php
@@ -0,0 +1,39 @@
+<?php
+/**
+*
+* This file is part of the phpBB Forum Software package.
+*
+* @copyright (c) phpBB Limited <https://www.phpbb.com>
+* @license GNU General Public License, version 2 (GPL-2.0)
+*
+* For full copyright and license information, please see
+* the docs/CREDITS.txt file.
+*
+*/
+
+namespace phpbb\db\migration\data\v330;
+
+class extensions_composer extends \phpbb\db\migration\migration
+{
+	public function update_data()
+	{
+		return array(
+			array('config.add', array('exts_composer_repositories', json_encode([
+				'https://www.phpbb.com/customise/db/composer/',
+			], JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES))),
+			array('config.add', array('exts_composer_packagist', false)),
+			array('config.add', array('exts_composer_json_file', 'composer-ext.json')),
+			array('config.add', array('exts_composer_vendor_dir', 'vendor-ext/')),
+			array('config.add', array('exts_composer_enable_on_install', false)),
+			array('config.add', array('exts_composer_purge_on_remove', true)),
+			array('module.add', array(
+				'acp',
+				'ACP_EXTENSION_MANAGEMENT',
+				array(
+					'module_basename'	=> 'acp_extensions',
+					'modes'				=> array('catalog'),
+				),
+			)),
+		);
+	}
+}
diff --git a/phpBB/phpbb/di/container_builder.php b/phpBB/phpbb/di/container_builder.php
index ac1a1a1733..c4cb64144b 100644
--- a/phpBB/phpbb/di/container_builder.php
+++ b/phpBB/phpbb/di/container_builder.php
@@ -415,6 +415,12 @@ class container_builder
 			$ext_container->register('cache.driver', '\\phpbb\\cache\\driver\\dummy');
 			$ext_container->compile();
 
+			$config = $ext_container->get('config');
+			if (@is_file($this->phpbb_root_path . $config['exts_composer_vendor_dir'] . '/autoload.php'))
+			{
+				require_once($this->phpbb_root_path . $config['exts_composer_vendor_dir'] . '/autoload.php');
+			}
+
 			$extensions = $ext_container->get('ext.manager')->all_enabled();
 
 			// Load each extension found
diff --git a/phpBB/phpbb/di/extension/container_configuration.php b/phpBB/phpbb/di/extension/container_configuration.php
index 4585d6509e..3870670ac0 100644
--- a/phpBB/phpbb/di/extension/container_configuration.php
+++ b/phpBB/phpbb/di/extension/container_configuration.php
@@ -45,6 +45,13 @@ class container_configuration implements ConfigurationInterface
 						->booleanNode('enable_debug_extension')->defaultValue(false)->end()
 					->end()
 				->end()
+				->arrayNode('extensions')
+					->addDefaultsIfNotSet()
+					->children()
+						->booleanNode('composer_debug')->defaultValue(false)->end()
+						->booleanNode('composer_verbose')->defaultValue(false)->end()
+					->end()
+				->end()
 			->end()
 		;
 		return $treeBuilder;
diff --git a/phpBB/phpbb/di/extension/core.php b/phpBB/phpbb/di/extension/core.php
index 67150f0103..64c3dafcad 100644
--- a/phpBB/phpbb/di/extension/core.php
+++ b/phpBB/phpbb/di/extension/core.php
@@ -15,6 +15,7 @@ namespace phpbb\di\extension;
 
 use Symfony\Component\Config\FileLocator;
 use Symfony\Component\Config\Resource\FileResource;
+use Symfony\Component\Console\Output\OutputInterface;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
 use Symfony\Component\DependencyInjection\Loader\YamlFileLoader;
 use Symfony\Component\HttpKernel\DependencyInjection\Extension;
@@ -92,6 +93,18 @@ class core extends Extension
 			$definition->addTag('twig.extension');
 		}
 
+		$composer_output = OutputInterface::VERBOSITY_NORMAL;
+		if ($config['extensions']['composer_verbose'])
+		{
+			$composer_output = OutputInterface::VERBOSITY_VERBOSE;
+		}
+		if ($config['extensions']['composer_debug'])
+		{
+			$composer_output = OutputInterface::VERBOSITY_DEBUG;
+		}
+
+		$container->setParameter('extensions.composer.output', $composer_output);
+
 		// Set the debug options
 		foreach ($config['debug'] as $name => $value)
 		{
diff --git a/phpBB/vendor-ext/.git-keep b/phpBB/vendor-ext/.git-keep
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/tests/di/fixtures/config/production/container/environment.yml b/tests/di/fixtures/config/production/container/environment.yml
index 8281d9e941..ba6b679795 100644
--- a/tests/di/fixtures/config/production/container/environment.yml
+++ b/tests/di/fixtures/config/production/container/environment.yml
@@ -19,6 +19,11 @@ services:
     ext.manager:
         class: phpbb\extension\manager_mock
 
+    config:
+        class: phpbb\config\config
+        arguments:
+            - []
+
     template.twig.environment:
         class: Exception
         arguments:
diff --git a/tests/di/fixtures/config/test/container/environment.yml b/tests/di/fixtures/config/test/container/environment.yml
index 252117dd32..97ebe4aee1 100644
--- a/tests/di/fixtures/config/test/container/environment.yml
+++ b/tests/di/fixtures/config/test/container/environment.yml
@@ -16,6 +16,11 @@ services:
     dispatcher:
         class: phpbb\db\driver\container_mock
 
+    config:
+        class: phpbb\config\config
+        arguments:
+            - []
+
     template.twig.environment:
         class: Exception
         arguments:
diff --git a/tests/di/fixtures/other_config/production/container/environment.yml b/tests/di/fixtures/other_config/production/container/environment.yml
index c0d2f87bab..aeb552eeb7 100644
--- a/tests/di/fixtures/other_config/production/container/environment.yml
+++ b/tests/di/fixtures/other_config/production/container/environment.yml
@@ -19,6 +19,11 @@ services:
     ext.manager:
         class: phpbb\extension\manager_mock
 
+    config:
+        class: phpbb\config\config
+        arguments:
+            - []
+
     template.twig.environment:
         class: Exception
         arguments: