Omnipay is a payment processing library for PHP. It has been designed based on ideas from Active Merchant, plus experience implementing dozens of gateways for [CI Merchant]. It has a clear and consistent API, is fully unit tested, and even comes with an example application to get you started.If you are using Symfony 3 (or Symfony 3 components), please note that Omnipay 2.x still relies on Guzzle3, which in turn depends on symfony/event-dispatcher 2.x. This conflicts with Symfony 3 (standard install), so cannot be installed. Development for Omnipay 3.x is still in progress at the moment.