Guzzle is a PHP HTTP client and framework for building RESTful web service clients
A bundle integrating Guzzle >=4.0 in Symfony
Behat API extension using Guzzle Service Descriptions to functionally test API endpoints
Segment.io PHP Library - using Guzzle 4
PHP OAuth 1/2 service classes using Guzzle
A Guzzle plugin that let's you debug everything in the Clockwork browser extension.