PRADO 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. A range of web applications have been built using the PRADO Framework.
There is a configurable and pluggable modular architecture and full spectrum of database support within PRADO. It supports AJAX-enabled Web components, Customizable and localizable error/exception handling and Generic caching modules and selective output caching. There is some sort of Security measures: cross-site script (XSS) prevention, cookie protection as well. Most importantly, Rich documentation and strong userbase will help you through.
The sole requirement to run PRADO-based applications is a Web server supporting PHP 5.1.0 or higher. PRADO is free. You can use it to develop either open source or commercial applications.