CakePHP: The Rapid Development Framework for PHP - Official Repository
The DokuWiki Open Source Wiki Engine
Laravel is a web application framework with expressive, elegant syntax. We’ve already laid the foundation for your next big idea — freeing you to create without sweating the small things.
Open Source PHP Framework (originally from EllisLab)
The missing Symfony Admin Generator
MODX Revolution - Content Management Framework
A customizable, open-source ecommerce platform built on WordPress. Build any commerce solution you can imagine.
Silverstripe CMS - this is a module for Silverstripe Framework rather than a standalone app. Use https://github.com/silverstripe/silverstripe-installer/ to set this up.
A free open source IT asset/license management system
Official repository for Concrete CMS development
Official repository of the AWS SDK for PHP (@awsforphp)
Home of the Joomla! Content Management System
:cloud: ownCloud web server core (Files, DAV, etc.)
MyBB is a free and open source forum software.