Silex is a PHP microframework for PHP 5.3. It is built on the shoulders of Symfony and Pimple and also inspired by Sinatra. A microframework provides the guts for building simple single-file apps. Silex aims to be: concise (it exposes an intuitive and concise API that is fun to use), extensible (it has an extension system based around the Pimple micro service-container that makes it even easier to tie in third party libraries) and testable (it uses Symfony's HttpKernel, which abstracts request and response and simplifies app testing).