Frameworks for PHP

Dwoo
Dwoo is a PHP 5 template engine positioned as an alternative to Smarty. It is (nearly) fully compatible with its templates and plug-ins, but it is being written from scratch and is aimed to go one step further with a cleaner code base.

http://dwoo.org/

CodeIgniter
CodeIgniter is a powerful, high-performance, open-source PHP framework that helps you author PHP applications rapidly. CodeIgniter is known for having a light footprint, thereby reducing your server’s work. 

http://codeigniter.com/

YII Framework
Here is a high-performance component-based PHP framework that is supposed to be more efficient than CodeIgniter, CakePHP, ZF and Symfony. An optimal solution for developing large-scale Web applications. Yii supports MVC, DAO/ActiveRecord, I18N/L10N, caching, jQuery-based AJAX support, authentication and role-based access control, scaffolding, input validation, widgets, events, theming and Web services.

http://www.yiiframework.com/

NetBeans
A dedicated PHP coding environment and complete integration with web standards. The NetBeans PHP editor is dynamically integrated with NetBeans HTML, JavaScript and CSS editing features such as syntax highlighting and the JavaScript debugger. NetBeans IDE 6.5 fully supports iterative development, so testing PHP projects follows the classic patterns familiar to web developers.

http://www.netbeans.org/features/php/index.html

Solar
Solar is a PHP 5 development framework for Web applications derived from the Savant templating engine. Solar uses the MVC architectural pattern and has a host of classes and functions for securing your Web app against SQL injection, cross-website scripting (XSS) and other common exploits. 

http://www.solarphp.com/

PEAR – PHP Extension and Application Repository
PEAR is a popular framework and distribution system for reusable PHP components. The purpose of the framework is to provide a structured library of open-source code for PHP users, a system for code distribution and package maintenance and a standard style for PHP code.

http://pear.php.net/

Propel
Propel is an Object-Relational Mapping (ORM) framework for PHP 5. It allows you to access your database using a set of objects, providing a simple API for storing and retrieving data.

http://propel.phpdb.org/trac/

Zend Framework
The Zend Framework by Zend Technologies (the creators of PHP’s scripting engine) is a popular PHP Web application framework that embraces the principles of PHP OOP; it’s very extensible and has built-in utilities for working with free Web service APIs, such as those of Google, Flickr and Amazon.

Qcodo
Qcodo is an excellent open-source PHP Web application framework. It’s subdivided into two parts: (1) Code Generator, and (2) Qforms. Code Generator handles the creation of object code and PHP and HTML front-end code from your data model. Qforms is an intuitive system for handling and creating complex PHP-driven HTML Web forms. Check out demos of applications that use Qcodo and presentational material that covers Qcodo. 

http://www.qcodo.com/

SAJAX
SAJAX is a JavaScript and AJAX application framework that works well with PHP (as well as several other server-side scripting languages). See SAJAX at work by going to Wall live demonstration.

Smarty

Smarty is a popular PHP templating system to help you separate PHP logic and front-end code (HTML, CSS, JavaScript). It will keep your projects modular and easier to maintain.

http://www.smarty.net/

CakePHP
CakePHP is one of the leading PHP frameworks for creating robust, fully-featured Web applications. CakePHP has an extensive and well-organized online manual. If you want to learn via video tutorials, check out the CakePHP screencasts.

http://cakephp.org/

PHPSpec

PHPSpec is a simple and intuitive PHP framework. It follows the Behavior-Driven Development principle and therefore allows you to write behavior-oriented code, oftentimes in plain English.