PHP Frameworks

1. CodeIgniter
CodeIgniter is a powerful PHP framework with a very small footprint, built for PHP coders who need a simple and elegant toolkit to create full-featured web applications.

2. CakePHP
CakePHP is a rapid development framework for PHP that provides an extensible architecture for developing, maintaining, and deploying applications.

3. Symfony
Symfony is a full-stack framework, a library of cohesive classes written in PHP5. It provides an architecture, components and tools for developers to build complex web applications faster. Choosing symfony allows you to release your applications earlier, host and scale them without problem, and maintain them over time with no surprise.

4. Prado
PRADOTM is a component-based and event-driven programming framework for developing Web applications in PHP 5. PRADO stands for PHP Rapid Application Development Object-oriented.

5. Qcodo
It is a completely object-oriented framework that takes the best of PHP and provides a truly rapid application development platform. Initial prototypes roll out in minutes instead of hours. Iterations come around in hours instead of days (or even weeks). As projects iterate into more cohesive solutions, the framework allows developers to take prototypes to the next level by providing the capability of bringing the application maturity.

6. Zend Framework
Zend Framework is focused on building more secure, reliable, and modern Web 2.0 applications & web services, and consuming widely available APIs from leading vendors like Google, Amazon, Yahoo!, Flickr, as well as API providers and cataloguers like StrikeIron and ProgrammableWeb.

7. Akelos
The Akelos PHP Framework is a web application development platform based on the MVC (Model View Controller) design pattern. Based on good practices, it allows you to:
Write views using Ajax easily, Control requests and responses through a controller, Manage internationalized applications, Communicate models and the database using simple conventions.

8. Maintainable
The Maintainable PHP Framework was originally built only for our own projects, then released to open source at the request of our customers. Like any framework, it's certainly not appropriate for every application. It's designed primarily for use with small- to mid- sized applications.

9. evoCore
evoCore is the framework at the heart of the b2evolution blogging application. It is freely available for anyone to use. It is dual licensed so you can choose to use it either under the GNU GPL or the Mozilla MPL license. (b2evo for example is using it under the GPL).

10. Stratos
The Stratos Framework is an open-source, object-oriented web application framework that facilitates the rapid development of well-organized, secure, and maintainable PHP web applications. Stratos frees you from working on tedious, routine tasks, and allows you to focus on specific software requirements.

11. Seagull
Seagull is a mature OOP framework for building web, command line and GUI applications. Licensed under BSD, the project allows PHP developers to easily integrate and manage code resources, and build complex applications quickly.

12. Zoop
The Zoop Framework is inclusive, cooperating with and containing components integrated from some existing projects including Smarty, the Prototype JS Framework, and a number of Pear Modules.

13. php.MVC
php.MVC implements the Model-View-Controller (MVC) design pattern, and encourages application design based on the Model 2 paradigm. This design model allows the Web page or other contents (View) to be mostly separated from the internal application code (Controller/Model), making it easier for designers and programmers to focus on their respective areas of expertise.

14. AjaxAC
AjaxAC is an open-source framework written in PHP, used to develop/create/generate AJAX applications. The fundamental idea behind AJAX (Asynchronous JavaScript And XML) is to use the XMLHttpRequest object to change a web page state using background HTTP sub-requests without reloading the entire page. It is released under the terms of the Apache License v2.0.

15. xAjax
xAjax is an open source PHP class library that allows to create quickly Ajax applications using HTML, CSS, JavaScript, and PHP.

16. PHOCOA
PHOCOA (pronounced faux-ko) is PHP framework for developing web applications. PHOCOA's primary intent is to make web application development in PHP easier, faster, and higher-quality.

17. Kohana
Kohana is a PHP 5 framework that uses the model view controller architectural pattern. It aims to be secure, lightweight, and easy to use.

18. Limb
Limb is an OpenSource(LGPL) PHP framework mostly aimed for rapid web application prototyping and development. The current actively developed branch of framework is Limb3(there is also Limb2 but it's not maintained anymore).

19. Solar
Solar is a PHP 5 framework for rapid application development. It is fully name-spaced and uses enterprise application design patterns, with built-in support for localization and configuration at all levels.

20. BlueShoes
BlueShoes is a comprehensive application framework and content management system. It is written in the widely used web-scripting language PHP. BlueShoes offers excellent support for the popular MySQL database as well as support for Oracle and MSSQL.