PHP On Pie is a PHP framework that combines the best ideas from PHP projects like Drupal, CodeIgniter, Kohana, and ZendFramework. It has very few core concepts: classes, models, events, slots, and tools. It lets you repackage completed apps into plugins that you or others can use later. Its smart database classes allow you to implement vertical and horizontal partitioning (sharding) easily to handle millions of users.
PSX is a PHP framework for creating RESTful APIs. It helps you to build clean URLs serving Web standard formats like JSON, XML, Atom, and RSS. It includes a handler system that abstracts away SQL queries from domain logic, a routing system that executes correct controller method for the location of the controller and the method annotation, and a flexible data system that converts database records into formats like JSON, XML, Atom, and RSS. A lightweight DI container handles dependencies. The controller supports request and response filters that can modify the HTTP request or response, and filters are provided for Basic and Oauth authentication.