diff --git a/src/flextype/Endpoints/Utils/access.php b/src/flextype/Endpoints/Utils/access.php
new file mode 100644
index 00000000..20039a24
--- /dev/null
+++ b/src/flextype/Endpoints/Utils/access.php
@@ -0,0 +1,20 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * Flextype (http://flextype.org)
+ * Founded by Sergey Romanenko and maintained by Flextype Community.
+ */
+
+namespace Flextype;
+
+use Flextype\Component\Filesystem\Filesystem;
+
+/**
+ * Validate access token
+ */
+function validate_access_token($token) : bool
+{
+    return Filesystem::has(PATH['project'] . '/tokens/access/' . $token . '/token.yaml');
+}
diff --git a/src/flextype/Endpoints/Utils/errors.php b/src/flextype/Endpoints/Utils/errors.php
new file mode 100644
index 00000000..d47f8090
--- /dev/null
+++ b/src/flextype/Endpoints/Utils/errors.php
@@ -0,0 +1,110 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * Flextype (http://flextype.org)
+ * Founded by Sergey Romanenko and maintained by Flextype Community.
+ */
+
+namespace Flextype;
+
+/**
+ * API errors
+ */
+$api_errors = [
+    '0000' => [
+        'http_status_code' => 500,
+        'message' => 'Internal Error',
+    ],
+    '0001' => [
+        'http_status_code' => 404,
+        'message' => 'Not Found',
+    ],
+    '0002' => [
+        'http_status_code' => 400,
+        'message' => 'Bad Request',
+    ],
+    '0003' => [
+        'http_status_code' => 401,
+        'message' => 'Unauthorized',
+    ],
+    '0100' => [
+        'http_status_code' => 400,
+        'message' => 'Wrong query params or not defined',
+    ],
+    '0101' => [
+        'http_status_code' => 400,
+        'message' => 'Wrong body params or not defined',
+    ],
+    '0102' => [
+        'http_status_code' => 404,
+        'message' => 'Entry not found',
+    ],
+    '0200' => [
+        'http_status_code' => 400,
+        'message' => 'Wrong query params or not defined',
+    ],
+    '0201' => [
+        'http_status_code' => 400,
+        'message' => 'Wrong body params or not defined',
+    ],
+    '0202' => [
+        'http_status_code' => 404,
+        'message' => 'Config item not found',
+    ],
+    '0300' => [
+        'http_status_code' => 400,
+        'message' => 'Wrong query params or not defined',
+    ],
+    '0301' => [
+        'http_status_code' => 400,
+        'message' => 'Wrong body params or not defined',
+    ],
+    '0302' => [
+        'http_status_code' => 404,
+        'message' => 'Registry item not found',
+    ],
+    '0400' => [
+        'http_status_code' => 400,
+        'message' => 'Wrong query params or not defined',
+    ],
+    '0401' => [
+        'http_status_code' => 400,
+        'message' => 'Wrong body params or not defined',
+    ],
+    '0402' => [
+        'http_status_code' => 404,
+        'message' => 'Image not found',
+    ],
+
+    '0501' => [
+        'http_status_code' => 400,
+        'message' => 'Wrong query params or not defined',
+    ],
+    '0501' => [
+        'http_status_code' => 400,
+        'message' => 'Wrong body params or not defined',
+    ],
+    '0502' => [
+        'http_status_code' => 404,
+        'message' => 'File not found',
+    ],
+
+    '0601' => [
+        'http_status_code' => 400,
+        'message' => 'Wrong query params or not defined',
+    ],
+    '0601' => [
+        'http_status_code' => 400,
+        'message' => 'Wrong body params or not defined',
+    ],
+    '0602' => [
+        'http_status_code' => 404,
+        'message' => 'Folder not found',
+    ],
+];
+
+
+$api_sys_messages['AccessTokenInvalid'] = ['sys' => ['type' => 'Error', 'id' => 'AccessTokenInvalid'], 'message' => 'The access token you sent could not be found or is invalid.'];
+$api_sys_messages['NotFound']           = ['sys' => ['type' => 'Error', 'id' => 'NotFound'], 'message' => 'The resource could not be found.'];
diff --git a/src/flextype/Endpoints/access.php b/src/flextype/Endpoints/access.php
deleted file mode 100644
index 173ef9ef..00000000
--- a/src/flextype/Endpoints/access.php
+++ /dev/null
@@ -1,28 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-/**
- * Flextype (http://flextype.org)
- * Founded by Sergey Romanenko and maintained by Flextype Community.
- */
-
-namespace Flextype;
-
-use Flextype\Component\Filesystem\Filesystem;
-use Psr\Http\Message\ResponseInterface as Response;
-use Psr\Http\Message\ServerRequestInterface as Request;
-
-/**
- * API sys messages
- */
-$api_sys_messages['AccessTokenInvalid'] = ['sys' => ['type' => 'Error', 'id' => 'AccessTokenInvalid'], 'message' => 'The access token you sent could not be found or is invalid.'];
-$api_sys_messages['NotFound'] = ['sys' => ['type' => 'Error', 'id' => 'NotFound'], 'message' => 'The resource could not be found.'];
-
-/**
- * Validate access token
- */
-function validate_access_token($token) : bool
-{
-    return Filesystem::has(PATH['project'] . '/tokens/access/' . $token . '/token.yaml');
-}
diff --git a/src/flextype/Endpoints/config.php b/src/flextype/Endpoints/config.php
index f0f21e1f..89ad8184 100644
--- a/src/flextype/Endpoints/config.php
+++ b/src/flextype/Endpoints/config.php
@@ -13,7 +13,6 @@ use Flextype\Component\Filesystem\Filesystem;
 use Psr\Http\Message\ResponseInterface as Response;
 use Psr\Http\Message\ServerRequestInterface as Request;
 use function array_replace_recursive;
-use function count;
 
 /**
  * Validate config token
@@ -36,18 +35,20 @@ function validate_config_token($token) : bool
  * Returns:
  * An array of config item objects.
  */
-$app->get('/api/config', function (Request $request, Response $response) use ($flextype, $api_sys_messages) {
-
+$app->get('/api/config', function (Request $request, Response $response) use ($flextype, $api_errors) {
     // Get Query Params
     $query = $request->getQueryParams();
 
+    if (! isset($query['id']) || ! isset($query['config']) || ! isset($query['token'])) {
+        return $response->withJson($api_errors['0200'], $api_errors['0200']['http_status_code']);
+    }
+
     // Set variables
-    $key      = $query['key'];
-    $config   = $query['config'];
-    $token    = $query['token'];
+    $key    = $query['key'];
+    $config = $query['config'];
+    $token  = $query['token'];
 
     if ($flextype['registry']->get('flextype.settings.api.config.enabled')) {
-
         // Validate config token
         if (validate_config_token($token)) {
             $delivery_config_token_file_path = PATH['project'] . '/tokens/config/' . $token . '/token.yaml';
@@ -56,7 +57,7 @@ $app->get('/api/config', function (Request $request, Response $response) use ($f
             if ($delivery_config_token_file_data = $flextype['serializer']->decode(Filesystem::read($delivery_config_token_file_path), 'yaml')) {
                 if ($delivery_config_token_file_data['state'] === 'disabled' ||
                     ($delivery_config_token_file_data['limit_calls'] !== 0 && $delivery_config_token_file_data['calls'] >= $delivery_config_token_file_data['limit_calls'])) {
-                    return $response->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                    return $response->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
                 }
 
                 // Fetch config
@@ -66,7 +67,6 @@ $app->get('/api/config', function (Request $request, Response $response) use ($f
 
                     // Set response code
                     $response_code = 200;
-
                 } else {
                     $response_data = [];
                     $response_code = 404;
@@ -75,11 +75,10 @@ $app->get('/api/config', function (Request $request, Response $response) use ($f
                 // Update calls counter
                 Filesystem::write($delivery_config_token_file_path, $flextype['serializer']->encode(array_replace_recursive($delivery_config_token_file_data, ['calls' => $delivery_config_token_file_data['calls'] + 1]), 'yaml'));
 
-                if ($response_code == 404) {
-
+                if ($response_code === 404) {
                     // Return response
                     return $response
-                           ->withJson($api_sys_messages['NotFound'], $response_code);
+                           ->withJson($api_errors['0202'], $api_errors['0202']['http_status_code']);
                 }
 
                 // Return response
@@ -88,15 +87,15 @@ $app->get('/api/config', function (Request $request, Response $response) use ($f
             }
 
             return $response
-                   ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                   ->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
         }
 
         return $response
-               ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+               ->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
     }
 
     return $response
-           ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+           ->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
 });
 
 
@@ -114,11 +113,14 @@ $app->get('/api/config', function (Request $request, Response $response) use ($f
  * Returns:
  * Returns the config item object for the config item that was just created.
  */
-$app->post('/api/config', function (Request $request, Response $response) use ($flextype, $api_sys_messages) {
-
+$app->post('/api/config', function (Request $request, Response $response) use ($flextype, $api_errors) {
     // Get Post Data
     $post_data = $request->getParsedBody();
 
+    if (! isset($post_data['token']) || ! isset($post_data['access_token']) || ! isset($post_data['config']) || ! isset($post_data['data'])) {
+        return $response->withJson($api_errors['0201'], $api_errors['0201']['http_status_code']);
+    }
+
     // Set variables
     $token        = $post_data['token'];
     $access_token = $post_data['access_token'];
@@ -126,7 +128,6 @@ $app->post('/api/config', function (Request $request, Response $response) use ($
     $data         = $post_data['data'];
 
     if ($flextype['registry']->get('flextype.settings.api.config.enabled')) {
-
         // Validate config and access token
         if (validate_config_token($token) && validate_access_token($access_token)) {
             $config_token_file_path = PATH['project'] . '/tokens/config/' . $token . '/token.yaml';
@@ -135,15 +136,14 @@ $app->post('/api/config', function (Request $request, Response $response) use ($
             // Set config and access token file
             if (($config_token_file_data = $flextype['serializer']->decode(Filesystem::read($config_token_file_path), 'yaml')) &&
                 ($access_token_file_data = $flextype['serializer']->decode(Filesystem::read($access_token_file_path), 'yaml'))) {
-
                 if ($config_token_file_data['state'] === 'disabled' ||
                     ($config_token_file_data['limit_calls'] !== 0 && $config_token_file_data['calls'] >= $config_token_file_data['limit_calls'])) {
-                    return $response->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                    return $response->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
                 }
 
                 if ($access_token_file_data['state'] === 'disabled' ||
                     ($access_token_file_data['limit_calls'] !== 0 && $access_token_file_data['calls'] >= $access_token_file_data['limit_calls'])) {
-                    return $response->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                    return $response->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
                 }
 
                 // Create config
@@ -151,7 +151,7 @@ $app->post('/api/config', function (Request $request, Response $response) use ($
 
                 if ($create_config) {
                     $response_data['data']['key']   = $data['key'];
-                    $response_data['data']['value'] = $flextype['config']->get($config, $data['key']);;
+                    $response_data['data']['value'] = $flextype['config']->get($config, $data['key']);
 
                     // Set response code
                     $response_code = 200;
@@ -161,16 +161,15 @@ $app->post('/api/config', function (Request $request, Response $response) use ($
                 }
 
                 // Set response code
-                $response_code = ($create_config) ? 200 : 404;
+                $response_code = $create_config ? 200 : 404;
 
                 // Update calls counter
                 Filesystem::write($config_token_file_path, $flextype['serializer']->encode(array_replace_recursive($config_token_file_data, ['calls' => $config_token_file_data['calls'] + 1]), 'yaml'));
 
-                if ($response_code == 404) {
-
+                if ($response_code === 404) {
                     // Return response
                     return $response
-                           ->withJson($api_sys_messages['NotFound'], $response_code);
+                           ->withJson($api_errors['0202'], $api_errors['0202']['http_status_code']);
                 }
 
                 // Return response
@@ -179,15 +178,15 @@ $app->post('/api/config', function (Request $request, Response $response) use ($
             }
 
             return $response
-                   ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                   ->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
         }
 
         return $response
-               ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+               ->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
     }
 
     return $response
-           ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+           ->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
 });
 
 /**
@@ -204,11 +203,14 @@ $app->post('/api/config', function (Request $request, Response $response) use ($
  * Returns:
  * Returns the config item object for the config item that was just created.
  */
-$app->patch('/api/config', function (Request $request, Response $response) use ($flextype, $api_sys_messages) {
-
+$app->patch('/api/config', function (Request $request, Response $response) use ($flextype, $api_errors) {
     // Get Post Data
     $post_data = $request->getParsedBody();
 
+    if (! isset($post_data['token']) || ! isset($post_data['access_token']) || ! isset($post_data['config']) || ! isset($post_data['data'])) {
+        return $response->withJson($api_errors['0201'], $api_errors['0201']['http_status_code']);
+    }
+
     // Set variables
     $token        = $post_data['token'];
     $access_token = $post_data['access_token'];
@@ -216,25 +218,22 @@ $app->patch('/api/config', function (Request $request, Response $response) use (
     $config       = $post_data['config'];
 
     if ($flextype['registry']->get('flextype.settings.api.config.enabled')) {
-
         // Validate config and access token
         if (validate_config_token($token) && validate_access_token($access_token)) {
-
             $config_token_file_path = PATH['project'] . '/tokens/config/' . $token . '/token.yaml';
             $access_token_file_path = PATH['project'] . '/tokens/access/' . $access_token . '/token.yaml';
 
             // Set config and access token file
             if (($config_token_file_data = $flextype['serializer']->decode(Filesystem::read($config_token_file_path), 'yaml')) &&
                 ($access_token_file_data = $flextype['serializer']->decode(Filesystem::read($access_token_file_path), 'yaml'))) {
-
                 if ($config_token_file_data['state'] === 'disabled' ||
                     ($config_token_file_data['limit_calls'] !== 0 && $config_token_file_data['calls'] >= $config_token_file_data['limit_calls'])) {
-                    return $response->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                    return $response->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
                 }
 
                 if ($access_token_file_data['state'] === 'disabled' ||
                     ($access_token_file_data['limit_calls'] !== 0 && $access_token_file_data['calls'] >= $access_token_file_data['limit_calls'])) {
-                    return $response->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                    return $response->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
                 }
 
                 // Update config
@@ -252,16 +251,15 @@ $app->patch('/api/config', function (Request $request, Response $response) use (
                 }
 
                 // Set response code
-                $response_code = ($update_config) ? 200 : 404;
+                $response_code = $update_config ? 200 : 404;
 
                 // Update calls counter
                 Filesystem::write($config_token_file_path, $flextype['serializer']->encode(array_replace_recursive($config_token_file_data, ['calls' => $config_token_file_data['calls'] + 1]), 'yaml'));
 
-                if ($response_code == 404) {
-
+                if ($response_code === 404) {
                     // Return response
                     return $response
-                           ->withJson($api_sys_messages['NotFound'], $response_code);
+                           ->withJson($api_errors['0202'], $api_errors['0202']['http_status_code']);
                 }
 
                 // Return response
@@ -270,16 +268,15 @@ $app->patch('/api/config', function (Request $request, Response $response) use (
             }
 
             return $response
-                   ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                   ->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
         }
 
         return $response
-               ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
-
+               ->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
     }
 
     return $response
-           ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+           ->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
 });
 
 /**
@@ -296,11 +293,14 @@ $app->patch('/api/config', function (Request $request, Response $response) use (
  * Returns:
  * Returns an empty body with HTTP status 204
  */
-$app->delete('/api/config', function (Request $request, Response $response) use ($flextype) {
-
+$app->delete('/api/config', function (Request $request, Response $response) use ($flextype, $api_errors) {
     // Get Post Data
     $post_data = $request->getParsedBody();
 
+    if (! isset($post_data['token']) || ! isset($post_data['access_token']) || ! isset($post_data['config']) || ! isset($post_data['data'])) {
+        return $response->withJson($api_errors['0201'], $api_errors['0201']['http_status_code']);
+    }
+
     // Set variables
     $token        = $post_data['token'];
     $access_token = $post_data['access_token'];
@@ -308,7 +308,6 @@ $app->delete('/api/config', function (Request $request, Response $response) use
     $config       = $post_data['config'];
 
     if ($flextype['registry']->get('flextype.settings.api.config.enabled')) {
-
         // Validate config and access token
         if (validate_config_token($token) && validate_access_token($access_token)) {
             $config_token_file_path = PATH['project'] . '/tokens/config/' . $token . '/token.yaml';
@@ -317,31 +316,29 @@ $app->delete('/api/config', function (Request $request, Response $response) use
             // Set config and access token file
             if (($config_token_file_data = $flextype['serializer']->decode(Filesystem::read($config_token_file_path), 'yaml')) &&
                 ($access_token_file_data = $flextype['serializer']->decode(Filesystem::read($access_token_file_path), 'yaml'))) {
-
                 if ($config_token_file_data['state'] === 'disabled' ||
                     ($config_token_file_data['limit_calls'] !== 0 && $config_token_file_data['calls'] >= $config_token_file_data['limit_calls'])) {
-                    return $response->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                    return $response->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
                 }
 
                 if ($access_token_file_data['state'] === 'disabled' ||
                     ($access_token_file_data['limit_calls'] !== 0 && $access_token_file_data['calls'] >= $access_token_file_data['limit_calls'])) {
-                    return $response->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                    return $response->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
                 }
 
                 // Delete entry
                 $delete_config = $flextype['config']->delete($config, $data['key']);
 
                 // Set response code
-                $response_code = ($delete_config) ? 204 : 404;
+                $response_code = $delete_config ? 204 : 404;
 
                 // Update calls counter
                 Filesystem::write($config_token_file_path, $flextype['serializer']->encode(array_replace_recursive($config_token_file_data, ['calls' => $config_token_file_data['calls'] + 1]), 'yaml'));
 
-                if ($response_code == 404) {
-
+                if ($response_code === 404) {
                     // Return response
                     return $response
-                           ->withJson($api_sys_messages['NotFound'], $response_code);
+                           ->withJson($api_errors['0202'], $api_errors['0202']['http_status_code']);
                 }
 
                 // Return response
@@ -350,13 +347,13 @@ $app->delete('/api/config', function (Request $request, Response $response) use
             }
 
             return $response
-                   ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                   ->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
         }
 
         return $response
-               ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+               ->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
     }
 
     return $response
-           ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+           ->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
 });
diff --git a/src/flextype/Endpoints/entries.php b/src/flextype/Endpoints/entries.php
index 263abfbc..87f93576 100644
--- a/src/flextype/Endpoints/entries.php
+++ b/src/flextype/Endpoints/entries.php
@@ -13,6 +13,7 @@ use Flextype\Component\Filesystem\Filesystem;
 use Psr\Http\Message\ResponseInterface as Response;
 use Psr\Http\Message\ServerRequestInterface as Request;
 use function array_replace_recursive;
+use function collect_filter;
 use function count;
 
 /**
@@ -36,31 +37,38 @@ function validate_entries_token($token) : bool
  * Returns:
  * An array of entry item objects.
  */
-$app->get('/api/entries', function (Request $request, Response $response) use ($flextype, $api_sys_messages) {
-
+$app->get('/api/entries', function (Request $request, Response $response) use ($flextype, $api_errors) {
     // Get Query Params
     $query = $request->getQueryParams();
 
+    if (! isset($query['id']) || ! isset($query['token'])) {
+        return $response->withJson($api_errors['0100'], $api_errors['0100']['http_status_code']);
+    }
+
     // Set variables
     $id     = $query['id'];
     $token  = $query['token'];
     $filter = $query['filter'] ?? null;
 
     if ($flextype['registry']->get('flextype.settings.api.entries.enabled')) {
-
         // Validate entries token
         if (validate_entries_token($token)) {
-            $entries_token_file_path = PATH['project'] . '/tokens/' . $token. '/token.yaml';
+            $entries_token_file_path = PATH['project'] . '/tokens/entries/' . $token . '/token.yaml';
 
             // Set entries token file
             if ($entries_token_file_data = $flextype['serializer']->decode(Filesystem::read($entries_token_file_path), 'yaml')) {
                 if ($entries_token_file_data['state'] === 'disabled' ||
                     ($entries_token_file_data['limit_calls'] !== 0 && $entries_token_file_data['calls'] >= $entries_token_file_data['limit_calls'])) {
-                    return $response->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                    return $response->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
                 }
 
-                // Fetch entry
-                $response_data['data'] = $flextype['entries']->fetch($id, $filter);
+                // Fetch entries collection
+                if ($filter !== null) {
+                    $response_data['data'] = collect_filter($flextype['entries']->fetch($id, true), $filter);
+                }
+
+                // Fetch single entry
+                $response_data['data'] = $flextype['entries']->fetch($id);
 
                 // Set response code
                 $response_code = count($response_data['data']) > 0 ? 200 : 404;
@@ -68,28 +76,22 @@ $app->get('/api/entries', function (Request $request, Response $response) use ($
                 // Update calls counter
                 Filesystem::write($entries_token_file_path, $flextype['serializer']->encode(array_replace_recursive($entries_token_file_data, ['calls' => $entries_token_file_data['calls'] + 1]), 'yaml'));
 
-                if ($response_code == 404) {
-
+                if ($response_code === 404) {
                     // Return response
-                    return $response
-                           ->withJson($api_sys_messages['NotFound'], $response_code);
+                    return $response->withJson($api_errors['0102'], $api_errors['0102']['http_status_code']);
                 }
 
                 // Return response
-                return $response
-                       ->withJson($response_data, $response_code);
+                return $response->withJson($response_data, $response_code);
             }
 
-            return $response
-                   ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+            return $response->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
         }
 
-        return $response
-               ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+        return $response->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
     }
 
-    return $response
-           ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+    return $response->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
 });
 
 /**
@@ -106,11 +108,14 @@ $app->get('/api/entries', function (Request $request, Response $response) use ($
  * Returns:
  * Returns the entry item object for the entry item that was just created.
  */
-$app->post('/api/entries', function (Request $request, Response $response) use ($flextype, $api_sys_messages) {
-
+$app->post('/api/entries', function (Request $request, Response $response) use ($flextype, $api_errors) {
     // Get Post Data
     $post_data = $request->getParsedBody();
 
+    if (! isset($post_data['token']) || ! isset($post_data['access_token']) || ! isset($post_data['id']) || ! isset($post_data['data'])) {
+        return $response->withJson($api_errors['0101'], $api_errors['0101']['http_status_code']);
+    }
+
     // Set variables
     $token        = $post_data['token'];
     $access_token = $post_data['access_token'];
@@ -118,24 +123,22 @@ $app->post('/api/entries', function (Request $request, Response $response) use (
     $data         = $post_data['data'];
 
     if ($flextype['registry']->get('flextype.settings.api.entries.enabled')) {
-
         // Validate entries and access token
         if (validate_entries_token($token) && validate_access_token($access_token)) {
             $entries_token_file_path = PATH['project'] . '/tokens/entries/' . $token . '/token.yaml';
-            $access_token_file_path = PATH['project'] . '/tokens/access/' . $access_token . '/token.yaml';
+            $access_token_file_path  = PATH['project'] . '/tokens/access/' . $access_token . '/token.yaml';
 
             // Set entries and access token file
             if (($entries_token_file_data = $flextype['serializer']->decode(Filesystem::read($entries_token_file_path), 'yaml')) &&
                 ($access_token_file_data = $flextype['serializer']->decode(Filesystem::read($access_token_file_path), 'yaml'))) {
-
                 if ($entries_token_file_data['state'] === 'disabled' ||
                     ($entries_token_file_data['limit_calls'] !== 0 && $entries_token_file_data['calls'] >= $entries_token_file_data['limit_calls'])) {
-                    return $response->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                    return $response->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
                 }
 
                 if ($access_token_file_data['state'] === 'disabled' ||
                     ($access_token_file_data['limit_calls'] !== 0 && $access_token_file_data['calls'] >= $access_token_file_data['limit_calls'])) {
-                    return $response->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                    return $response->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
                 }
 
                 // Create entry
@@ -148,16 +151,15 @@ $app->post('/api/entries', function (Request $request, Response $response) use (
                 }
 
                 // Set response code
-                $response_code = ($create_entry) ? 200 : 404;
+                $response_code = $create_entry ? 200 : 404;
 
                 // Update calls counter
                 Filesystem::write($entries_token_file_path, $flextype['serializer']->encode(array_replace_recursive($entries_token_file_data, ['calls' => $entries_token_file_data['calls'] + 1]), 'yaml'));
 
-                if ($response_code == 404) {
-
+                if ($response_code === 404) {
                     // Return response
                     return $response
-                           ->withJson($api_sys_messages['NotFound'], $response_code);
+                           ->withJson($api_errors['0102'], $api_errors['0102']['http_status_code']);
                 }
 
                 // Return response
@@ -166,15 +168,15 @@ $app->post('/api/entries', function (Request $request, Response $response) use (
             }
 
             return $response
-                   ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                   ->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
         }
 
         return $response
-               ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+               ->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
     }
 
     return $response
-           ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+           ->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
 });
 
 /**
@@ -191,11 +193,14 @@ $app->post('/api/entries', function (Request $request, Response $response) use (
  * Returns:
  * Returns the entry item object for the entry item that was just updated.
  */
-$app->patch('/api/entries', function (Request $request, Response $response) use ($flextype) {
-
+$app->patch('/api/entries', function (Request $request, Response $response) use ($flextype, $api_errors) {
     // Get Post Data
     $post_data = $request->getParsedBody();
 
+    if (! isset($post_data['token']) || ! isset($post_data['access_token']) || ! isset($post_data['id']) || ! isset($post_data['data'])) {
+        return $response->withJson($api_errors['0101'], $api_errors['0101']['http_status_code']);
+    }
+
     // Set variables
     $token        = $post_data['token'];
     $access_token = $post_data['access_token'];
@@ -203,24 +208,22 @@ $app->patch('/api/entries', function (Request $request, Response $response) use
     $data         = $post_data['data'];
 
     if ($flextype['registry']->get('flextype.settings.api.entries.enabled')) {
-
         // Validate entries and access token
         if (validate_entries_token($token) && validate_access_token($access_token)) {
             $entries_token_file_path = PATH['project'] . '/tokens/entries/' . $token . '/token.yaml';
-            $access_token_file_path = PATH['project'] . '/tokens/access/' . $access_token . '/token.yaml';
+            $access_token_file_path  = PATH['project'] . '/tokens/access/' . $access_token . '/token.yaml';
 
             // Set entries and access token file
             if (($entries_token_file_data = $flextype['serializer']->decode(Filesystem::read($entries_token_file_path), 'yaml')) &&
                 ($access_token_file_data = $flextype['serializer']->decode(Filesystem::read($access_token_file_path), 'yaml'))) {
-
                 if ($entries_token_file_data['state'] === 'disabled' ||
                     ($entries_token_file_data['limit_calls'] !== 0 && $entries_token_file_data['calls'] >= $entries_token_file_data['limit_calls'])) {
-                    return $response->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                    return $response->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
                 }
 
                 if ($access_token_file_data['state'] === 'disabled' ||
                     ($access_token_file_data['limit_calls'] !== 0 && $access_token_file_data['calls'] >= $access_token_file_data['limit_calls'])) {
-                    return $response->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                    return $response->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
                 }
 
                 // Update entry
@@ -233,16 +236,15 @@ $app->patch('/api/entries', function (Request $request, Response $response) use
                 }
 
                 // Set response code
-                $response_code = ($update_entry) ? 200 : 404;
+                $response_code = $update_entry ? 200 : 404;
 
                 // Update calls counter
                 Filesystem::write($entries_token_file_path, $flextype['serializer']->encode(array_replace_recursive($entries_token_file_data, ['calls' => $entries_token_file_data['calls'] + 1]), 'yaml'));
 
-                if ($response_code == 404) {
-
+                if ($response_code === 404) {
                     // Return response
                     return $response
-                           ->withJson($api_sys_messages['NotFound'], $response_code);
+                           ->withJson($api_errors['0102'], $api_errors['0102']['http_status_code']);
                 }
 
                 // Return response
@@ -251,15 +253,15 @@ $app->patch('/api/entries', function (Request $request, Response $response) use
             }
 
             return $response
-                   ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                   ->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
         }
 
         return $response
-               ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+               ->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
     }
 
     return $response
-           ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+           ->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
 });
 
 /**
@@ -276,36 +278,37 @@ $app->patch('/api/entries', function (Request $request, Response $response) use
  * Returns:
  * Returns the entry item object for the entry item that was just renamed.
  */
-$app->put('/api/entries', function (Request $request, Response $response) use ($flextype) {
-
+$app->put('/api/entries', function (Request $request, Response $response) use ($flextype, $api_errors) {
     // Get Post Data
     $post_data = $request->getParsedBody();
 
+    if (! isset($post_data['token']) || ! isset($post_data['access_token']) || ! isset($post_data['id']) || ! isset($post_data['new_id'])) {
+        return $response->withJson($api_errors['0101'], $api_errors['0101']['http_status_code']);
+    }
+
     // Set variables
-    $token         = $post_data['token'];
-    $access_token  = $post_data['access_token'];
-    $id            = $post_data['id'];
-    $new_id        = $post_data['new_id'];
+    $token        = $post_data['token'];
+    $access_token = $post_data['access_token'];
+    $id           = $post_data['id'];
+    $new_id       = $post_data['new_id'];
 
     if ($flextype['registry']->get('flextype.settings.api.entries.enabled')) {
-
         // Validate entries and access token
         if (validate_entries_token($token) && validate_access_token($access_token)) {
             $entries_token_file_path = PATH['project'] . '/tokens/entries/' . $token . '/token.yaml';
-            $access_token_file_path = PATH['project'] . '/tokens/access/' . $access_token . '/token.yaml';
+            $access_token_file_path  = PATH['project'] . '/tokens/access/' . $access_token . '/token.yaml';
 
             // Set entries and access token file
             if (($entries_token_file_data = $flextype['serializer']->decode(Filesystem::read($entries_token_file_path), 'yaml')) &&
                 ($access_token_file_data = $flextype['serializer']->decode(Filesystem::read($access_token_file_path), 'yaml'))) {
-
                 if ($entries_token_file_data['state'] === 'disabled' ||
                     ($entries_token_file_data['limit_calls'] !== 0 && $entries_token_file_data['calls'] >= $entries_token_file_data['limit_calls'])) {
-                    return $response->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                    return $response->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
                 }
 
                 if ($access_token_file_data['state'] === 'disabled' ||
                     ($access_token_file_data['limit_calls'] !== 0 && $access_token_file_data['calls'] >= $access_token_file_data['limit_calls'])) {
-                    return $response->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                    return $response->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
                 }
 
                 // Rename entry
@@ -319,16 +322,15 @@ $app->put('/api/entries', function (Request $request, Response $response) use ($
                 }
 
                 // Set response code
-                $response_code = ($rename_entry) ? 200 : 404;
+                $response_code = $rename_entry ? 200 : 404;
 
                 // Update calls counter
                 Filesystem::write($entries_token_file_path, $flextype['serializer']->encode(array_replace_recursive($entries_token_file_data, ['calls' => $entries_token_file_data['calls'] + 1]), 'yaml'));
 
-                if ($response_code == 404) {
-
+                if ($response_code === 404) {
                     // Return response
                     return $response
-                           ->withJson($api_sys_messages['NotFound'], $response_code);
+                           ->withJson($api_errors['0102'], $api_errors['0102']['http_status_code']);
                 }
 
                 // Return response
@@ -337,15 +339,15 @@ $app->put('/api/entries', function (Request $request, Response $response) use ($
             }
 
             return $response
-                   ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                   ->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
         }
 
         return $response
-               ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+               ->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
     }
 
     return $response
-           ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+           ->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
 });
 
 /**
@@ -362,36 +364,37 @@ $app->put('/api/entries', function (Request $request, Response $response) use ($
  * Returns:
  * Returns the entry item object for the entry item that was just copied.
  */
-$app->put('/api/entries/copy', function (Request $request, Response $response) use ($flextype) {
-
+$app->put('/api/entries/copy', function (Request $request, Response $response) use ($flextype, $api_errors) {
     // Get Post Data
     $post_data = $request->getParsedBody();
 
+    if (! isset($post_data['token']) || ! isset($post_data['access_token']) || ! isset($post_data['id']) || ! isset($post_data['new_id'])) {
+        return $response->withJson($api_errors['0101'], $api_errors['0101']['http_status_code']);
+    }
+
     // Set variables
-    $token         = $post_data['token'];
-    $access_token  = $post_data['access_token'];
-    $id            = $post_data['id'];
-    $new_id        = $post_data['new_id'];
+    $token        = $post_data['token'];
+    $access_token = $post_data['access_token'];
+    $id           = $post_data['id'];
+    $new_id       = $post_data['new_id'];
 
     if ($flextype['registry']->get('flextype.settings.api.entries.enabled')) {
-
         // Validate entries and access token
         if (validate_entries_token($token) && validate_access_token($access_token)) {
             $entries_token_file_path = PATH['project'] . '/tokens/entries/' . $token . '/token.yaml';
-            $access_token_file_path = PATH['project'] . '/tokens/access/' . $access_token . '/token.yaml';
+            $access_token_file_path  = PATH['project'] . '/tokens/access/' . $access_token . '/token.yaml';
 
             // Set entries and access token file
             if (($entries_token_file_data = $flextype['serializer']->decode(Filesystem::read($entries_token_file_path), 'yaml')) &&
                 ($access_token_file_data = $flextype['serializer']->decode(Filesystem::read($access_token_file_path), 'yaml'))) {
-
                 if ($entries_token_file_data['state'] === 'disabled' ||
                     ($entries_token_file_data['limit_calls'] !== 0 && $entries_token_file_data['calls'] >= $entries_token_file_data['limit_calls'])) {
-                    return $response->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                    return $response->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
                 }
 
                 if ($access_token_file_data['state'] === 'disabled' ||
                     ($access_token_file_data['limit_calls'] !== 0 && $access_token_file_data['calls'] >= $access_token_file_data['limit_calls'])) {
-                    return $response->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                    return $response->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
                 }
 
                 // Copy entry
@@ -405,16 +408,15 @@ $app->put('/api/entries/copy', function (Request $request, Response $response) u
                 }
 
                 // Set response code
-                $response_code = ($copy_entry) ? 200 : 404;
+                $response_code = $copy_entry ? 200 : 404;
 
                 // Update calls counter
                 Filesystem::write($entries_token_file_path, $flextype['serializer']->encode(array_replace_recursive($entries_token_file_data, ['calls' => $entries_token_file_data['calls'] + 1]), 'yaml'));
 
-                if ($response_code == 404) {
-
+                if ($response_code === 404) {
                     // Return response
                     return $response
-                           ->withJson($api_sys_messages['NotFound'], $response_code);
+                           ->withJson($api_errors['0102'], $api_errors['0102']['http_status_code']);
                 }
 
                 // Return response
@@ -423,15 +425,15 @@ $app->put('/api/entries/copy', function (Request $request, Response $response) u
             }
 
             return $response
-                   ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                   ->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
         }
 
         return $response
-               ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+               ->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
     }
 
     return $response
-           ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+           ->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
 });
 
 /**
@@ -447,51 +449,51 @@ $app->put('/api/entries/copy', function (Request $request, Response $response) u
  * Returns:
  * Returns an empty body with HTTP status 204
  */
-$app->delete('/api/entries', function (Request $request, Response $response) use ($flextype) {
-
+$app->delete('/api/entries', function (Request $request, Response $response) use ($flextype, $api_errors) {
     // Get Post Data
     $post_data = $request->getParsedBody();
 
+    if (! isset($post_data['token']) || ! isset($post_data['access_token']) || ! isset($post_data['id'])) {
+        return $response->withJson($api_errors['0101'], $api_errors['0101']['http_status_code']);
+    }
+
     // Set variables
     $token        = $post_data['token'];
     $access_token = $post_data['access_token'];
     $id           = $post_data['id'];
 
     if ($flextype['registry']->get('flextype.settings.api.entries.enabled')) {
-
         // Validate entries and access token
         if (validate_entries_token($token) && validate_access_token($access_token)) {
             $entries_token_file_path = PATH['project'] . '/tokens/entries/' . $token . '/token.yaml';
-            $access_token_file_path = PATH['project'] . '/tokens/access/' . $access_token . '/token.yaml';
+            $access_token_file_path  = PATH['project'] . '/tokens/access/' . $access_token . '/token.yaml';
 
             // Set entries and access token file
             if (($entries_token_file_data = $flextype['serializer']->decode(Filesystem::read($entries_token_file_path), 'yaml')) &&
                 ($access_token_file_data = $flextype['serializer']->decode(Filesystem::read($access_token_file_path), 'yaml'))) {
-
                 if ($entries_token_file_data['state'] === 'disabled' ||
                     ($entries_token_file_data['limit_calls'] !== 0 && $entries_token_file_data['calls'] >= $entries_token_file_data['limit_calls'])) {
-                    return $response->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                    return $response->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
                 }
 
                 if ($access_token_file_data['state'] === 'disabled' ||
                     ($access_token_file_data['limit_calls'] !== 0 && $access_token_file_data['calls'] >= $access_token_file_data['limit_calls'])) {
-                    return $response->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                    return $response->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
                 }
 
                 // Delete entry
                 $delete_entry = $flextype['entries']->delete($id);
 
                 // Set response code
-                $response_code = ($delete_entry) ? 204 : 404;
+                $response_code = $delete_entry ? 204 : 404;
 
                 // Update calls counter
                 Filesystem::write($entries_token_file_path, $flextype['serializer']->encode(array_replace_recursive($entries_token_file_data, ['calls' => $entries_token_file_data['calls'] + 1]), 'yaml'));
 
-                if ($response_code == 404) {
-
+                if ($response_code === 404) {
                     // Return response
                     return $response
-                           ->withJson($api_sys_messages['NotFound'], $response_code);
+                           ->withJson($api_errors['0102'], $api_errors['0102']['http_status_code']);
                 }
 
                 // Return response
@@ -500,13 +502,13 @@ $app->delete('/api/entries', function (Request $request, Response $response) use
             }
 
             return $response
-                   ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                   ->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
         }
 
         return $response
-               ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+               ->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
     }
 
     return $response
-           ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+           ->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
 });
diff --git a/src/flextype/Endpoints/files.php b/src/flextype/Endpoints/files.php
index e9c809b5..eef41274 100644
--- a/src/flextype/Endpoints/files.php
+++ b/src/flextype/Endpoints/files.php
@@ -13,6 +13,9 @@ use Flextype\Component\Filesystem\Filesystem;
 use Psr\Http\Message\ResponseInterface as Response;
 use Psr\Http\Message\ServerRequestInterface as Request;
 use function array_replace_recursive;
+use function basename;
+use function count;
+use function is_dir;
 
 /**
  * Validate files token
@@ -35,25 +38,27 @@ function validate_files_token($token) : bool
  * An array of file item objects.
  */
 $app->get('/api/files', function (Request $request, Response $response) use ($flextype, $api_sys_messages) {
-
     // Get Query Params
     $query = $request->getQueryParams();
 
+    if (! isset($query['path']) || ! isset($query['token'])) {
+        return $response->withJson($api_errors['0500'], $api_errors['0500']['http_status_code']);
+    }
+
     // Set variables
     $path  = $query['path'];
     $token = $query['token'];
 
     if ($flextype['registry']->get('flextype.settings.api.files.enabled')) {
-
         // Validate delivery token
         if (validate_files_token($token)) {
-            $delivery_files_token_file_path = PATH['project'] . '/tokens/files/' . $token. '/token.yaml';
+            $delivery_files_token_file_path = PATH['project'] . '/tokens/files/' . $token . '/token.yaml';
 
             // Set delivery token file
             if ($delivery_files_token_file_data = $flextype['serializer']->decode(Filesystem::read($delivery_files_token_file_path), 'yaml')) {
                 if ($delivery_files_token_file_data['state'] === 'disabled' ||
                     ($delivery_files_token_file_data['limit_calls'] !== 0 && $delivery_files_token_file_data['calls'] >= $delivery_files_token_file_data['limit_calls'])) {
-                    return $response->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                    return $response->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
                 }
 
                 // Create files array
@@ -75,8 +80,7 @@ $app->get('/api/files', function (Request $request, Response $response) use ($fl
                 // Update calls counter
                 Filesystem::write($delivery_files_token_file_path, $flextype['serializer']->encode(array_replace_recursive($delivery_files_token_file_data, ['calls' => $delivery_files_token_file_data['calls'] + 1]), 'yaml'));
 
-                if ($response_code == 404) {
-
+                if ($response_code === 404) {
                     // Return response
                     return $response
                            ->withJson($api_sys_messages['NotFound'], $response_code);
@@ -114,10 +118,13 @@ $app->get('/api/files', function (Request $request, Response $response) use ($fl
  * Returns the file object for the file that was just created.
  */
 $app->post('/api/files', function (Request $request, Response $response) use ($flextype, $api_sys_messages) {
-
     // Get Post Data
     $post_data = $request->getParsedBody();
 
+    if (! isset($post_data['path']) || ! isset($post_data['access_token']) || ! isset($post_data['folder']) || !isset($_FILES['file'])) {
+        return $response->withJson($api_errors['0501'], $api_errors['0501']['http_status_code']);
+    }
+
     // Set variables
     $token        = $post_data['token'];
     $access_token = $post_data['access_token'];
@@ -125,24 +132,22 @@ $app->post('/api/files', function (Request $request, Response $response) use ($f
     $file         = $_FILES['file'];
 
     if ($flextype['registry']->get('flextype.settings.api.files.enabled')) {
-
         // Validate files and access token
         if (validate_files_token($token) && validate_access_token($access_token)) {
-            $files_token_file_path = PATH['project'] . '/tokens/files/' . $token . '/token.yaml';
+            $files_token_file_path  = PATH['project'] . '/tokens/files/' . $token . '/token.yaml';
             $access_token_file_path = PATH['project'] . '/tokens/access/' . $access_token . '/token.yaml';
 
             // Set files and access token file
             if (($files_token_file_data = $flextype['serializer']->decode(Filesystem::read($files_token_file_path), 'yaml')) &&
                 ($access_token_file_data = $flextype['serializer']->decode(Filesystem::read($access_token_file_path), 'yaml'))) {
-
                 if ($files_token_file_data['state'] === 'disabled' ||
                     ($files_token_file_data['limit_calls'] !== 0 && $files_token_file_data['calls'] >= $files_token_file_data['limit_calls'])) {
-                    return $response->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                    return $response->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
                 }
 
                 if ($access_token_file_data['state'] === 'disabled' ||
                     ($access_token_file_data['limit_calls'] !== 0 && $access_token_file_data['calls'] >= $access_token_file_data['limit_calls'])) {
-                    return $response->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                    return $response->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
                 }
 
                 // Create file
@@ -155,7 +160,7 @@ $app->post('/api/files', function (Request $request, Response $response) use ($f
                 }
 
                 // Set response code
-                $response_code = (Filesystem::has($create_file)) ? 200 : 404;
+                $response_code = Filesystem::has($create_file) ? 200 : 404;
 
                 // Return response
                 return $response
@@ -164,8 +169,7 @@ $app->post('/api/files', function (Request $request, Response $response) use ($f
                 // Update calls counter
                 Filesystem::write($files_token_file_path, $flextype['serializer']->encode(array_replace_recursive($files_token_file_data, ['calls' => $files_token_file_data['calls'] + 1]), 'yaml'));
 
-                if ($response_code == 404) {
-
+                if ($response_code === 404) {
                     // Return response
                     return $response
                            ->withJson($api_sys_messages['NotFound'], $response_code);
@@ -204,10 +208,13 @@ $app->post('/api/files', function (Request $request, Response $response) use ($f
  * Returns the file object for the file that was just created.
  */
 $app->put('/api/files', function (Request $request, Response $response) use ($flextype, $api_sys_messages) {
-
     // Get Post Data
     $post_data = $request->getParsedBody();
 
+    if (! isset($post_data['path']) || ! isset($post_data['access_token']) || ! isset($post_data['id']) || ! isset($post_data['new_id'])) {
+        return $response->withJson($api_errors['0501'], $api_errors['0501']['http_status_code']);
+    }
+
     // Set variables
     $token        = $post_data['token'];
     $access_token = $post_data['access_token'];
@@ -215,24 +222,22 @@ $app->put('/api/files', function (Request $request, Response $response) use ($fl
     $new_id       = $post_data['new_id'];
 
     if ($flextype['registry']->get('flextype.settings.api.files.enabled')) {
-
         // Validate files and access token
         if (validate_files_token($token) && validate_access_token($access_token)) {
-            $files_token_file_path = PATH['project'] . '/tokens/files/' . $token . '/token.yaml';
+            $files_token_file_path  = PATH['project'] . '/tokens/files/' . $token . '/token.yaml';
             $access_token_file_path = PATH['project'] . '/tokens/access/' . $access_token . '/token.yaml';
 
             // Set files and access token file
             if (($files_token_file_data = $flextype['serializer']->decode(Filesystem::read($files_token_file_path), 'yaml')) &&
                 ($access_token_file_data = $flextype['serializer']->decode(Filesystem::read($access_token_file_path), 'yaml'))) {
-
                 if ($files_token_file_data['state'] === 'disabled' ||
                     ($files_token_file_data['limit_calls'] !== 0 && $files_token_file_data['calls'] >= $files_token_file_data['limit_calls'])) {
-                    return $response->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                    return $response->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
                 }
 
                 if ($access_token_file_data['state'] === 'disabled' ||
                     ($access_token_file_data['limit_calls'] !== 0 && $access_token_file_data['calls'] >= $access_token_file_data['limit_calls'])) {
-                    return $response->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                    return $response->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
                 }
 
                 // Rename file
@@ -245,7 +250,7 @@ $app->put('/api/files', function (Request $request, Response $response) use ($fl
                 }
 
                 // Set response code
-                $response_code = (Filesystem::has($rename_file)) ? 200 : 404;
+                $response_code = Filesystem::has($rename_file) ? 200 : 404;
 
                 // Return response
                 return $response
@@ -254,8 +259,7 @@ $app->put('/api/files', function (Request $request, Response $response) use ($fl
                 // Update calls counter
                 Filesystem::write($files_token_file_path, $flextype['serializer']->encode(array_replace_recursive($files_token_file_data, ['calls' => $files_token_file_data['calls'] + 1]), 'yaml'));
 
-                if ($response_code == 404) {
-
+                if ($response_code === 404) {
                     // Return response
                     return $response
                            ->withJson($api_sys_messages['NotFound'], $response_code);
@@ -292,47 +296,47 @@ $app->put('/api/files', function (Request $request, Response $response) use ($fl
  * Returns an empty body with HTTP status 204
  */
 $app->delete('/api/files', function (Request $request, Response $response) use ($flextype) {
-
     // Get Post Data
     $post_data = $request->getParsedBody();
 
+    if (! isset($post_data['path']) || ! isset($post_data['access_token']) || ! isset($post_data['id'])) {
+        return $response->withJson($api_errors['0501'], $api_errors['0501']['http_status_code']);
+    }
+
     // Set variables
     $token        = $post_data['token'];
     $access_token = $post_data['access_token'];
     $id           = $post_data['id'];
 
     if ($flextype['registry']->get('flextype.settings.api.files.enabled')) {
-
         // Validate files and access token
         if (validate_files_token($token) && validate_access_token($access_token)) {
-            $files_token_file_path = PATH['project'] . '/tokens/files/' . $token . '/token.yaml';
+            $files_token_file_path  = PATH['project'] . '/tokens/files/' . $token . '/token.yaml';
             $access_token_file_path = PATH['project'] . '/tokens/access/' . $access_token . '/token.yaml';
 
             // Set files and access token file
             if (($files_token_file_data = $flextype['serializer']->decode(Filesystem::read($files_token_file_path), 'yaml')) &&
                 ($access_token_file_data = $flextype['serializer']->decode(Filesystem::read($access_token_file_path), 'yaml'))) {
-
                 if ($files_token_file_data['state'] === 'disabled' ||
                     ($files_token_file_data['limit_calls'] !== 0 && $files_token_file_data['calls'] >= $files_token_file_data['limit_calls'])) {
-                    return $response->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                    return $response->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
                 }
 
                 if ($access_token_file_data['state'] === 'disabled' ||
                     ($access_token_file_data['limit_calls'] !== 0 && $access_token_file_data['calls'] >= $access_token_file_data['limit_calls'])) {
-                    return $response->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                    return $response->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
                 }
 
                 // Delete file
                 $delete_file = $flextype['media_files']->delete($id);
 
                 // Set response code
-                $response_code = ($delete_file) ? 204 : 404;
+                $response_code = $delete_file ? 204 : 404;
 
                 // Update calls counter
                 Filesystem::write($files_token_file_path, $flextype['serializer']->encode(array_replace_recursive($files_token_file_data, ['calls' => $files_token_file_data['calls'] + 1]), 'yaml'));
 
-                if ($response_code == 404) {
-
+                if ($response_code === 404) {
                     // Return response
                     return $response
                            ->withJson($api_sys_messages['NotFound'], $response_code);
@@ -371,10 +375,13 @@ $app->delete('/api/files', function (Request $request, Response $response) use (
  * Returns the file object for the file that was just created.
  */
 $app->patch('/api/files/meta', function (Request $request, Response $response) use ($flextype, $api_sys_messages) {
-
     // Get Post Data
     $post_data = $request->getParsedBody();
 
+    if (! isset($post_data['token']) || ! isset($post_data['access_token']) || ! isset($post_data['path']) || ! isset($post_data['field']) || ! isset($post_data['value'])) {
+        return $response->withJson($api_errors['0501'], $api_errors['0501']['http_status_code']);
+    }
+
     // Set variables
     $token        = $post_data['token'];
     $access_token = $post_data['access_token'];
@@ -383,24 +390,22 @@ $app->patch('/api/files/meta', function (Request $request, Response $response) u
     $value        = $post_data['value'];
 
     if ($flextype['registry']->get('flextype.settings.api.files.enabled')) {
-
         // Validate files and access token
         if (validate_files_token($token) && validate_access_token($access_token)) {
-            $files_token_file_path = PATH['project'] . '/tokens/files/' . $token . '/token.yaml';
+            $files_token_file_path  = PATH['project'] . '/tokens/files/' . $token . '/token.yaml';
             $access_token_file_path = PATH['project'] . '/tokens/access/' . $access_token . '/token.yaml';
 
             // Set files and access token file
             if (($files_token_file_data = $flextype['serializer']->decode(Filesystem::read($files_token_file_path), 'yaml')) &&
                 ($access_token_file_data = $flextype['serializer']->decode(Filesystem::read($access_token_file_path), 'yaml'))) {
-
                 if ($files_token_file_data['state'] === 'disabled' ||
                     ($files_token_file_data['limit_calls'] !== 0 && $files_token_file_data['calls'] >= $files_token_file_data['limit_calls'])) {
-                    return $response->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                    return $response->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
                 }
 
                 if ($access_token_file_data['state'] === 'disabled' ||
                     ($access_token_file_data['limit_calls'] !== 0 && $access_token_file_data['calls'] >= $access_token_file_data['limit_calls'])) {
-                    return $response->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                    return $response->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
                 }
 
                 // Update file meta
@@ -413,7 +418,7 @@ $app->patch('/api/files/meta', function (Request $request, Response $response) u
                 }
 
                 // Set response code
-                $response_code = ($update_file_meta) ? 200 : 404;
+                $response_code = $update_file_meta ? 200 : 404;
 
                 // Return response
                 return $response
@@ -422,8 +427,7 @@ $app->patch('/api/files/meta', function (Request $request, Response $response) u
                 // Update calls counter
                 Filesystem::write($files_token_file_path, $flextype['serializer']->encode(array_replace_recursive($files_token_file_data, ['calls' => $files_token_file_data['calls'] + 1]), 'yaml'));
 
-                if ($response_code == 404) {
-
+                if ($response_code === 404) {
                     // Return response
                     return $response
                            ->withJson($api_sys_messages['NotFound'], $response_code);
@@ -462,10 +466,13 @@ $app->patch('/api/files/meta', function (Request $request, Response $response) u
  * Returns the file object for the file that was just created.
  */
 $app->post('/api/files/meta', function (Request $request, Response $response) use ($flextype, $api_sys_messages) {
-
     // Get Post Data
     $post_data = $request->getParsedBody();
 
+    if (! isset($post_data['token']) || ! isset($post_data['access_token']) || ! isset($post_data['path']) || ! isset($post_data['field']) || ! isset($post_data['value'])) {
+        return $response->withJson($api_errors['0501'], $api_errors['0501']['http_status_code']);
+    }
+
     // Set variables
     $token        = $post_data['token'];
     $access_token = $post_data['access_token'];
@@ -474,24 +481,22 @@ $app->post('/api/files/meta', function (Request $request, Response $response) us
     $value        = $post_data['value'];
 
     if ($flextype['registry']->get('flextype.settings.api.files.enabled')) {
-
         // Validate files and access token
         if (validate_files_token($token) && validate_access_token($access_token)) {
-            $files_token_file_path = PATH['project'] . '/tokens/files/' . $token . '/token.yaml';
+            $files_token_file_path  = PATH['project'] . '/tokens/files/' . $token . '/token.yaml';
             $access_token_file_path = PATH['project'] . '/tokens/access/' . $access_token . '/token.yaml';
 
             // Set files and access token file
             if (($files_token_file_data = $flextype['serializer']->decode(Filesystem::read($files_token_file_path), 'yaml')) &&
                 ($access_token_file_data = $flextype['serializer']->decode(Filesystem::read($access_token_file_path), 'yaml'))) {
-
                 if ($files_token_file_data['state'] === 'disabled' ||
                     ($files_token_file_data['limit_calls'] !== 0 && $files_token_file_data['calls'] >= $files_token_file_data['limit_calls'])) {
-                    return $response->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                    return $response->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
                 }
 
                 if ($access_token_file_data['state'] === 'disabled' ||
                     ($access_token_file_data['limit_calls'] !== 0 && $access_token_file_data['calls'] >= $access_token_file_data['limit_calls'])) {
-                    return $response->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                    return $response->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
                 }
 
                 // Add file meta
@@ -504,7 +509,7 @@ $app->post('/api/files/meta', function (Request $request, Response $response) us
                 }
 
                 // Set response code
-                $response_code = ($add_file_meta) ? 200 : 404;
+                $response_code = $add_file_meta ? 200 : 404;
 
                 // Return response
                 return $response
@@ -513,8 +518,7 @@ $app->post('/api/files/meta', function (Request $request, Response $response) us
                 // Update calls counter
                 Filesystem::write($files_token_file_path, $flextype['serializer']->encode(array_replace_recursive($files_token_file_data, ['calls' => $files_token_file_data['calls'] + 1]), 'yaml'));
 
-                if ($response_code == 404) {
-
+                if ($response_code === 404) {
                     // Return response
                     return $response
                            ->withJson($api_sys_messages['NotFound'], $response_code);
@@ -553,10 +557,13 @@ $app->post('/api/files/meta', function (Request $request, Response $response) us
  * Returns the file object for the file that was just created.
  */
 $app->delete('/api/files/meta', function (Request $request, Response $response) use ($flextype, $api_sys_messages) {
-
     // Get Post Data
     $post_data = $request->getParsedBody();
 
+    if (! isset($post_data['token']) || ! isset($post_data['access_token']) || ! isset($post_data['path']) || ! isset($post_data['field'])) {
+        return $response->withJson($api_errors['0501'], $api_errors['0501']['http_status_code']);
+    }
+
     // Set variables
     $token        = $post_data['token'];
     $access_token = $post_data['access_token'];
@@ -564,24 +571,22 @@ $app->delete('/api/files/meta', function (Request $request, Response $response)
     $field        = $post_data['field'];
 
     if ($flextype['registry']->get('flextype.settings.api.files.enabled')) {
-
         // Validate files and access token
         if (validate_files_token($token) && validate_access_token($access_token)) {
-            $files_token_file_path = PATH['project'] . '/tokens/files/' . $token . '/token.yaml';
+            $files_token_file_path  = PATH['project'] . '/tokens/files/' . $token . '/token.yaml';
             $access_token_file_path = PATH['project'] . '/tokens/access/' . $access_token . '/token.yaml';
 
             // Set files and access token file
             if (($files_token_file_data = $flextype['serializer']->decode(Filesystem::read($files_token_file_path), 'yaml')) &&
                 ($access_token_file_data = $flextype['serializer']->decode(Filesystem::read($access_token_file_path), 'yaml'))) {
-
                 if ($files_token_file_data['state'] === 'disabled' ||
                     ($files_token_file_data['limit_calls'] !== 0 && $files_token_file_data['calls'] >= $files_token_file_data['limit_calls'])) {
-                    return $response->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                    return $response->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
                 }
 
                 if ($access_token_file_data['state'] === 'disabled' ||
                     ($access_token_file_data['limit_calls'] !== 0 && $access_token_file_data['calls'] >= $access_token_file_data['limit_calls'])) {
-                    return $response->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                    return $response->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
                 }
 
                 // Delete file meta
@@ -594,7 +599,7 @@ $app->delete('/api/files/meta', function (Request $request, Response $response)
                 }
 
                 // Set response code
-                $response_code = ($delete_file_meta) ? 200 : 404;
+                $response_code = $delete_file_meta ? 200 : 404;
 
                 // Return response
                 return $response
@@ -603,8 +608,7 @@ $app->delete('/api/files/meta', function (Request $request, Response $response)
                 // Update calls counter
                 Filesystem::write($files_token_file_path, $flextype['serializer']->encode(array_replace_recursive($files_token_file_data, ['calls' => $files_token_file_data['calls'] + 1]), 'yaml'));
 
-                if ($response_code == 404) {
-
+                if ($response_code === 404) {
                     // Return response
                     return $response
                            ->withJson($api_sys_messages['NotFound'], $response_code);
diff --git a/src/flextype/Endpoints/folders.php b/src/flextype/Endpoints/folders.php
index 505158a8..41a467c2 100644
--- a/src/flextype/Endpoints/folders.php
+++ b/src/flextype/Endpoints/folders.php
@@ -13,6 +13,7 @@ use Flextype\Component\Filesystem\Filesystem;
 use Psr\Http\Message\ResponseInterface as Response;
 use Psr\Http\Message\ServerRequestInterface as Request;
 use function array_replace_recursive;
+use function count;
 
 /**
  * Validate folders token
@@ -36,7 +37,6 @@ function validate_folders_token($token) : bool
  * An array of folder(s) item objects.
  */
 $app->get('/api/folders', function (Request $request, Response $response) use ($flextype, $api_sys_messages) {
-
     // Get Query Params
     $query = $request->getQueryParams();
 
@@ -46,25 +46,24 @@ $app->get('/api/folders', function (Request $request, Response $response) use ($
     $token = $query['token'];
 
     if ($flextype['registry']->get('flextype.settings.api.folders.enabled')) {
-
         // Validate delivery token
         if (validate_folders_token($token)) {
-            $folders_token_file_path = PATH['project'] . '/tokens/folders/' . $token. '/token.yaml';
+            $folders_token_file_path = PATH['project'] . '/tokens/folders/' . $token . '/token.yaml';
 
             // Set delivery token file
             if ($folders_token_file_data = $flextype['serializer']->decode(Filesystem::read($folders_token_file_path), 'yaml')) {
                 if ($folders_token_file_data['state'] === 'disabled' ||
                     ($folders_token_file_data['limit_calls'] !== 0 && $folders_token_file_data['calls'] >= $folders_token_file_data['limit_calls'])) {
-                    return $response->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                    return $response->withJson($api_errors['0501'], $api_errors['0501']['http_status_code']);
                 }
 
                 // Create folders array
                 $folders = [];
 
                 // Get list if folder or fodlers for specific folder
-                if ($mode == 'collection') {
+                if ($mode === 'collection') {
                     $folders = $flextype['media_folders']->fetchCollection($path);
-                } elseif ($mode == 'single') {
+                } elseif ($mode === 'single') {
                     $folders = $flextype['media_folders']->fetchSingle($path);
                 }
 
@@ -77,8 +76,7 @@ $app->get('/api/folders', function (Request $request, Response $response) use ($
                 // Update calls counter
                 Filesystem::write($folders_token_file_path, $flextype['serializer']->encode(array_replace_recursive($folders_token_file_data, ['calls' => $folders_token_file_data['calls'] + 1]), 'yaml'));
 
-                if ($response_code == 404) {
-
+                if ($response_code === 404) {
                     // Return response
                     return $response
                            ->withJson($api_sys_messages['NotFound'], $response_code);
@@ -116,76 +114,72 @@ $app->get('/api/folders', function (Request $request, Response $response) use ($
  * Returns the file object for the file that was just created.
  */
 $app->post('/api/folders', function (Request $request, Response $response) use ($flextype, $api_sys_messages) {
-
   // Get Post Data
-  $post_data = $request->getParsedBody();
+    $post_data = $request->getParsedBody();
 
   // Set variables
-  $token        = $post_data['token'];
-  $access_token = $post_data['access_token'];
-  $path         = $post_data['path'];
+    $token        = $post_data['token'];
+    $access_token = $post_data['access_token'];
+    $path         = $post_data['path'];
 
-  if ($flextype['registry']->get('flextype.settings.api.files.enabled')) {
+    if ($flextype['registry']->get('flextype.settings.api.files.enabled')) {
+        // Validate files and access token
+        if (validate_files_token($token) && validate_access_token($access_token)) {
+            $files_token_file_path  = PATH['project'] . '/tokens/files/' . $token . '/token.yaml';
+            $access_token_file_path = PATH['project'] . '/tokens/access/' . $access_token . '/token.yaml';
 
-      // Validate files and access token
-      if (validate_files_token($token) && validate_access_token($access_token)) {
-          $files_token_file_path = PATH['project'] . '/tokens/files/' . $token . '/token.yaml';
-          $access_token_file_path = PATH['project'] . '/tokens/access/' . $access_token . '/token.yaml';
-
-          // Set files and access token file
-          if (($files_token_file_data = $flextype['serializer']->decode(Filesystem::read($files_token_file_path), 'yaml')) &&
+            // Set files and access token file
+            if (($files_token_file_data = $flextype['serializer']->decode(Filesystem::read($files_token_file_path), 'yaml')) &&
               ($access_token_file_data = $flextype['serializer']->decode(Filesystem::read($access_token_file_path), 'yaml'))) {
-
-              if ($files_token_file_data['state'] === 'disabled' ||
+                if ($files_token_file_data['state'] === 'disabled' ||
                   ($files_token_file_data['limit_calls'] !== 0 && $files_token_file_data['calls'] >= $files_token_file_data['limit_calls'])) {
-                  return $response->withJson($api_sys_messages['AccessTokenInvalid'], 401);
-              }
+                    return $response->withJson($api_errors['0501'], $api_errors['0501']['http_status_code']);
+                }
 
-              if ($access_token_file_data['state'] === 'disabled' ||
+                if ($access_token_file_data['state'] === 'disabled' ||
                   ($access_token_file_data['limit_calls'] !== 0 && $access_token_file_data['calls'] >= $access_token_file_data['limit_calls'])) {
-                  return $response->withJson($api_sys_messages['AccessTokenInvalid'], 401);
-              }
+                    return $response->withJson($api_errors['0501'], $api_errors['0501']['http_status_code']);
+                }
 
-              // Create folder
-              $create_folder = $flextype['media_folders']->create($path);
+                // Create folder
+                $create_folder = $flextype['media_folders']->create($path);
 
-              if ($create_folder) {
-                  $response_data['data'] = $flextype['media_folders']->fetch($path);
-              } else {
-                  $response_data['data'] = [];
-              }
+                if ($create_folder) {
+                    $response_data['data'] = $flextype['media_folders']->fetch($path);
+                } else {
+                    $response_data['data'] = [];
+                }
 
-              // Set response code
-              $response_code = ($create_folder) ? 200 : 404;
+                // Set response code
+                $response_code = $create_folder ? 200 : 404;
 
-              // Return response
-              return $response
+                // Return response
+                return $response
                      ->withJson($response_data, $response_code);
 
-              // Update calls counter
-              Filesystem::write($files_token_file_path, $flextype['serializer']->encode(array_replace_recursive($files_token_file_data, ['calls' => $files_token_file_data['calls'] + 1]), 'yaml'));
+                // Update calls counter
+                Filesystem::write($files_token_file_path, $flextype['serializer']->encode(array_replace_recursive($files_token_file_data, ['calls' => $files_token_file_data['calls'] + 1]), 'yaml'));
 
-              if ($response_code == 404) {
-
-                  // Return response
-                  return $response
+                if ($response_code === 404) {
+                    // Return response
+                    return $response
                          ->withJson($api_sys_messages['NotFound'], $response_code);
-              }
+                }
 
-              // Return response
-              return $response
+                // Return response
+                return $response
                      ->withJson($response_data, $response_code);
-          }
+            }
 
-          return $response
+            return $response
                  ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
-      }
+        }
 
-      return $response
+        return $response
              ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
-  }
+    }
 
-  return $response
+    return $response
          ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
 });
 
@@ -204,77 +198,73 @@ $app->post('/api/folders', function (Request $request, Response $response) use (
  * Returns the file object for the file that was just created.
  */
 $app->put('/api/folders', function (Request $request, Response $response) use ($flextype, $api_sys_messages) {
-
   // Get Post Data
-  $post_data = $request->getParsedBody();
+    $post_data = $request->getParsedBody();
 
   // Set variables
-  $token        = $post_data['token'];
-  $access_token = $post_data['access_token'];
-  $id           = $post_data['id'];
-  $new_id       = $post_data['new_id'];
+    $token        = $post_data['token'];
+    $access_token = $post_data['access_token'];
+    $id           = $post_data['id'];
+    $new_id       = $post_data['new_id'];
 
-  if ($flextype['registry']->get('flextype.settings.api.files.enabled')) {
+    if ($flextype['registry']->get('flextype.settings.api.files.enabled')) {
+        // Validate files and access token
+        if (validate_files_token($token) && validate_access_token($access_token)) {
+            $files_token_file_path  = PATH['project'] . '/tokens/files/' . $token . '/token.yaml';
+            $access_token_file_path = PATH['project'] . '/tokens/access/' . $access_token . '/token.yaml';
 
-      // Validate files and access token
-      if (validate_files_token($token) && validate_access_token($access_token)) {
-          $files_token_file_path = PATH['project'] . '/tokens/files/' . $token . '/token.yaml';
-          $access_token_file_path = PATH['project'] . '/tokens/access/' . $access_token . '/token.yaml';
-
-          // Set files and access token file
-          if (($files_token_file_data = $flextype['serializer']->decode(Filesystem::read($files_token_file_path), 'yaml')) &&
+            // Set files and access token file
+            if (($files_token_file_data = $flextype['serializer']->decode(Filesystem::read($files_token_file_path), 'yaml')) &&
               ($access_token_file_data = $flextype['serializer']->decode(Filesystem::read($access_token_file_path), 'yaml'))) {
-
-              if ($files_token_file_data['state'] === 'disabled' ||
+                if ($files_token_file_data['state'] === 'disabled' ||
                   ($files_token_file_data['limit_calls'] !== 0 && $files_token_file_data['calls'] >= $files_token_file_data['limit_calls'])) {
-                  return $response->withJson($api_sys_messages['AccessTokenInvalid'], 401);
-              }
+                    return $response->withJson($api_errors['0501'], $api_errors['0501']['http_status_code']);
+                }
 
-              if ($access_token_file_data['state'] === 'disabled' ||
+                if ($access_token_file_data['state'] === 'disabled' ||
                   ($access_token_file_data['limit_calls'] !== 0 && $access_token_file_data['calls'] >= $access_token_file_data['limit_calls'])) {
-                  return $response->withJson($api_sys_messages['AccessTokenInvalid'], 401);
-              }
+                    return $response->withJson($api_errors['0501'], $api_errors['0501']['http_status_code']);
+                }
 
-              // Rename folder
-              $rename_folder = $flextype['media_folders']->rename($id, $new_id);
+                // Rename folder
+                $rename_folder = $flextype['media_folders']->rename($id, $new_id);
 
-              if ($rename_folder) {
-                  $response_data['data'] = $flextype['media_folders']->fetch($new_id);
-              } else {
-                  $response_data['data'] = [];
-              }
+                if ($rename_folder) {
+                    $response_data['data'] = $flextype['media_folders']->fetch($new_id);
+                } else {
+                    $response_data['data'] = [];
+                }
 
-              // Set response code
-              $response_code = ($rename_folder) ? 200 : 404;
+                // Set response code
+                $response_code = $rename_folder ? 200 : 404;
 
-              // Return response
-              return $response
+                // Return response
+                return $response
                      ->withJson($response_data, $response_code);
 
-              // Update calls counter
-              Filesystem::write($files_token_file_path, $flextype['serializer']->encode(array_replace_recursive($files_token_file_data, ['calls' => $files_token_file_data['calls'] + 1]), 'yaml'));
+                // Update calls counter
+                Filesystem::write($files_token_file_path, $flextype['serializer']->encode(array_replace_recursive($files_token_file_data, ['calls' => $files_token_file_data['calls'] + 1]), 'yaml'));
 
-              if ($response_code == 404) {
-
-                  // Return response
-                  return $response
+                if ($response_code === 404) {
+                    // Return response
+                    return $response
                          ->withJson($api_sys_messages['NotFound'], $response_code);
-              }
+                }
 
-              // Return response
-              return $response
+                // Return response
+                return $response
                      ->withJson($response_data, $response_code);
-          }
+            }
 
-          return $response
+            return $response
                  ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
-      }
+        }
 
-      return $response
+        return $response
              ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
-  }
+    }
 
-  return $response
+    return $response
          ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
 });
 
@@ -292,65 +282,61 @@ $app->put('/api/folders', function (Request $request, Response $response) use ($
 * Returns an empty body with HTTP status 204
 */
 $app->delete('/api/folders', function (Request $request, Response $response) use ($flextype) {
-
   // Get Post Data
-  $post_data = $request->getParsedBody();
+    $post_data = $request->getParsedBody();
 
   // Set variables
-  $token        = $post_data['token'];
-  $access_token = $post_data['access_token'];
-  $id           = $post_data['id'];
+    $token        = $post_data['token'];
+    $access_token = $post_data['access_token'];
+    $id           = $post_data['id'];
 
-  if ($flextype['registry']->get('flextype.settings.api.files.enabled')) {
+    if ($flextype['registry']->get('flextype.settings.api.files.enabled')) {
+        // Validate files and access token
+        if (validate_files_token($token) && validate_access_token($access_token)) {
+            $files_token_file_path  = PATH['project'] . '/tokens/files/' . $token . '/token.yaml';
+            $access_token_file_path = PATH['project'] . '/tokens/access/' . $access_token . '/token.yaml';
 
-      // Validate files and access token
-      if (validate_files_token($token) && validate_access_token($access_token)) {
-          $files_token_file_path = PATH['project'] . '/tokens/files/' . $token . '/token.yaml';
-          $access_token_file_path = PATH['project'] . '/tokens/access/' . $access_token . '/token.yaml';
-
-          // Set files and access token file
-          if (($files_token_file_data = $flextype['serializer']->decode(Filesystem::read($files_token_file_path), 'yaml')) &&
+            // Set files and access token file
+            if (($files_token_file_data = $flextype['serializer']->decode(Filesystem::read($files_token_file_path), 'yaml')) &&
               ($access_token_file_data = $flextype['serializer']->decode(Filesystem::read($access_token_file_path), 'yaml'))) {
-
-              if ($files_token_file_data['state'] === 'disabled' ||
+                if ($files_token_file_data['state'] === 'disabled' ||
                   ($files_token_file_data['limit_calls'] !== 0 && $files_token_file_data['calls'] >= $files_token_file_data['limit_calls'])) {
-                  return $response->withJson($api_sys_messages['AccessTokenInvalid'], 401);
-              }
+                    return $response->withJson($api_errors['0501'], $api_errors['0501']['http_status_code']);
+                }
 
-              if ($access_token_file_data['state'] === 'disabled' ||
+                if ($access_token_file_data['state'] === 'disabled' ||
                   ($access_token_file_data['limit_calls'] !== 0 && $access_token_file_data['calls'] >= $access_token_file_data['limit_calls'])) {
-                  return $response->withJson($api_sys_messages['AccessTokenInvalid'], 401);
-              }
+                    return $response->withJson($api_errors['0501'], $api_errors['0501']['http_status_code']);
+                }
 
-              // Delete folder
-              $delete_folder = $flextype['media_folders']->delete($id);
+                // Delete folder
+                $delete_folder = $flextype['media_folders']->delete($id);
 
-              // Set response code
-              $response_code = ($delete_folder) ? 204 : 404;
+                // Set response code
+                $response_code = $delete_folder ? 204 : 404;
 
-              // Update calls counter
-              Filesystem::write($files_token_file_path, $flextype['serializer']->encode(array_replace_recursive($files_token_file_data, ['calls' => $files_token_file_data['calls'] + 1]), 'yaml'));
+                // Update calls counter
+                Filesystem::write($files_token_file_path, $flextype['serializer']->encode(array_replace_recursive($files_token_file_data, ['calls' => $files_token_file_data['calls'] + 1]), 'yaml'));
 
-              if ($response_code == 404) {
-
-                  // Return response
-                  return $response
+                if ($response_code === 404) {
+                    // Return response
+                    return $response
                          ->withJson($api_sys_messages['NotFound'], $response_code);
-              }
+                }
 
-              // Return response
-              return $response
+                // Return response
+                return $response
                      ->withJson($delete_file, $response_code);
-          }
+            }
 
-          return $response
+            return $response
                  ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
-      }
+        }
 
-      return $response
+        return $response
              ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
-  }
+    }
 
-  return $response
+    return $response
          ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
 });
diff --git a/src/flextype/Endpoints/images.php b/src/flextype/Endpoints/images.php
index 38d365ea..1f323ebb 100644
--- a/src/flextype/Endpoints/images.php
+++ b/src/flextype/Endpoints/images.php
@@ -37,26 +37,27 @@ function validate_images_token($token) : bool
  * Returns:
  * Image file
  */
-$app->get('/api/images/{path:.+}', function (Request $request, Response $response, $args) use ($flextype, $api_sys_messages) {
-
+$app->get('/api/images/{path:.+}', function (Request $request, Response $response, $args) use ($flextype) {
     // Get Query Params
     $query = $request->getQueryParams();
 
+    if (! isset($query['token'])) {
+        return $response->withJson($api_errors['0400'], $api_errors['0400']['http_status_code']);
+    }
+
     // Set variables
     $token = $query['token'];
 
     if ($flextype['registry']->get('flextype.settings.api.images.enabled')) {
-
         // Validate delivery image token
         if (validate_images_token($token)) {
             $delivery_images_token_file_path = PATH['project'] . '/tokens/images/' . $token . '/token.yaml';
 
             // Set delivery token file
             if ($delivery_images_token_file_data = $flextype['serializer']->decode(Filesystem::read($delivery_images_token_file_path), 'yaml')) {
-
                 if ($delivery_images_token_file_data['state'] === 'disabled' ||
                     ($delivery_images_token_file_data['limit_calls'] !== 0 && $delivery_images_token_file_data['calls'] >= $delivery_images_token_file_data['limit_calls'])) {
-                    return $response->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                    return $response->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
                 }
 
                 // Update calls counter
@@ -69,17 +70,17 @@ $app->get('/api/images/{path:.+}', function (Request $request, Response $respons
                 }
 
                 return $response
-                    ->withJson($api_sys_messages['NotFound'], 404);
+                    ->withJson($api_errors['0402'], $api_errors['0402']['http_status_code']);
             }
 
             return $response
-                   ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                   ->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
         }
 
         return $response
-               ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+               ->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
     }
 
     return $response
-           ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+           ->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
 });
diff --git a/src/flextype/Endpoints/registry.php b/src/flextype/Endpoints/registry.php
index 57f734dc..d22deead 100644
--- a/src/flextype/Endpoints/registry.php
+++ b/src/flextype/Endpoints/registry.php
@@ -34,17 +34,19 @@ function validate_registry_token($token) : bool
  * Returns:
  * An array of registry item objects.
  */
-$app->get('/api/registry', function (Request $request, Response $response) use ($flextype, $api_sys_messages) {
-
+$app->get('/api/registry', function (Request $request, Response $response) use ($flextype) {
     // Get Query Params
     $query = $request->getQueryParams();
 
+    if (! isset($query['id']) || ! isset($query['token'])) {
+        return $response->withJson($api_errors['0300'], $api_errors['0300']['http_status_code']);
+    }
+
     // Set variables
     $id    = $query['id'];
     $token = $query['token'];
 
     if ($flextype['registry']->get('flextype.settings.api.registry.enabled')) {
-
         // Validate  token
         if (validate_registry_token($token)) {
             $registry_token_file_path = PATH['project'] . '/tokens/registry/' . $token . '/token.yaml';
@@ -53,7 +55,7 @@ $app->get('/api/registry', function (Request $request, Response $response) use (
             if ($registry_token_file_data = $flextype['serializer']->decode(Filesystem::read($registry_token_file_path), 'yaml')) {
                 if ($registry_token_file_data['state'] === 'disabled' ||
                     ($registry_token_file_data['limit_calls'] !== 0 && $registry_token_file_data['calls'] >= $registry_token_file_data['limit_calls'])) {
-                    return $response->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                    return $response->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
                 }
 
                 // Fetch registry
@@ -63,7 +65,6 @@ $app->get('/api/registry', function (Request $request, Response $response) use (
 
                     // Set response code
                     $response_code = 200;
-
                 } else {
                     $response_data = [];
                     $response_code = 404;
@@ -72,11 +73,10 @@ $app->get('/api/registry', function (Request $request, Response $response) use (
                 // Update calls counter
                 Filesystem::write($registry_token_file_path, $flextype['serializer']->encode(array_replace_recursive($registry_token_file_data, ['calls' => $registry_token_file_data['calls'] + 1]), 'yaml'));
 
-                if ($response_code == 404) {
-
+                if ($response_code === 404) {
                     // Return response
                     return $response
-                           ->withJson($api_sys_messages['NotFound'], $response_code);
+                           ->withJson($api_errors['0302'], $api_errors['0302']['http_status_code']);
                 }
 
                 // Return response
@@ -85,13 +85,13 @@ $app->get('/api/registry', function (Request $request, Response $response) use (
             }
 
             return $response
-                   ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+                   ->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
         }
 
         return $response
-               ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+               ->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
     }
 
     return $response
-           ->withJson($api_sys_messages['AccessTokenInvalid'], 401);
+           ->withJson($api_errors['0003'], $api_errors['0003']['http_status_code']);
 });