Simple interface for building query strings, POST requests, streaming large uploads, streaming large downloads, using HTTP cookies, uploading JSON data, etc...
Can send both synchronous and asynchronous requests using the same interface.
Uses PSR-7 interfaces for requests, responses, and streams. This allows you to utilize other PSR-7 compatible libraries with Guzzle.
Abstracts away the underlying HTTP transport, allowing you to write environment and transport agnostic code; i.e., no hard dependency on cURL, PHP streams, sockets, or non-blocking event loops.
Middleware system allows you to augment and compose client behavior.

$client = new \GuzzleHttp\Client();
$res = $client->request('GET', 'https://api.github.com/user', [
    'auth' => ['user', 'pass']
]);
echo $res->getStatusCode();
// 200
echo $res->getHeaderLine('content-type');
// 'application/json; charset=utf8'
echo $res->getBody();
// {"type":"User"...'

// Send an asynchronous request.
$request = new \GuzzleHttp\Psr7\Request('GET', 'http://httpbin.org');
$promise = $client->sendAsync($request)->then(function ($response) {
    echo 'I completed! ' . $response->getBody();
});
$promise->wait();

Help and docs

Installing Guzzle

The recommended way to install Guzzle is through Composer.

# Install Composer
curl -sS https://getcomposer.org/installer | php

Next, run the Composer command to install the latest stable version of Guzzle:

php composer.phar require guzzlehttp/guzzle

After installing, you need to require Composer's autoloader:

require 'vendor/autoload.php';

You can then later update Guzzle using composer:

composer.phar update

Version Guidance

Version	Status	Packagist	Namespace	Repo	Docs	PSR-7
3.x	EOL	`guzzle/guzzle`	`Guzzle`	v3	v3	No
4.x	EOL	`guzzlehttp/guzzle`	`GuzzleHttp`	N/A	N/A	No
5.x	Maintained	`guzzlehttp/guzzle`	`GuzzleHttp`	v5	v5	No
6.x	Latest	`guzzlehttp/guzzle`	`GuzzleHttp`	v6	v6	Yes