CodeIgniter – Open Source PHP Web Application Framework

CodeIgniter is an Application Development Framework/Toolkit for people who want to create full-featured web applications using PHP. Its goal is to enable you to develop projects much faster than you could if you were writing code from scratch, by providing a rich set of libraries for commonly needed tasks, as well as a simple interface and logical structure to access these libraries. CodeIgniter lets you creatively focus on your project by minimizing the amount of code needed for a given task.

Requirements: PHP version 4.3.2 or newer with Database
Demo: http://codeigniter.com/tutorials/
License: License Free