Open-source PHP applications can be used from managing databases to shopping, writing blogs to sending emails. Here is a list of few very popular open source PHP based applications:
osCommerce
osCommerce is an open source e-commerce solution under on going development by the open source community. Its feature packed out-of-the- box installation allows store owners to setup, run, and maintain their online stores with minimum effort and with no costs involved. osCommerce combines open source solutions to provide a free and open development platform, which includes the powerful PHP web scripting language, the stable Apache web server, and the fast MySQL database server.
phpBB
phpBB is a fast, efficient discussion board program built in PHP with a muti-database backend. Features include: posting, replying, private messages, polls, username/ip banning, strong encryption for storing passwords, user rankings, very advanced access control for private forums, full templating, simple yet robust translation system and much more.
Drupal
Drupal is a modular content management system, forum, blogging and community engine. It is database driven and can be used with MySQL, MySQLi and PostgreSQL. Its features include (but are not limited to) discussion forums, Web-based administration, theme support, a submission queue, content rating, content versioning, taxonomy support, user management with a fine-grained permission system based on user roles (groups), error logging, support for content syndication, locale support, and much more. It is considered to be an excellent platform for developers due to its clean code and extensibility, and it can also be used as a Web application framework.
Wordpress
WordPress is a state-of-the-art, semantic, personal publishing platform with a focus on aesthetics, Web standards, and usability. It was born out of a desire for an elegant, well-architected personal publishing system. While primarily geared towards functioning as a Weblog, WordPress is also a flexible CMS capable of managing many types of Web sites. In addition to the basic blog functions, it also has an integrated link manager (e.g. for blogrolls), file attachments, XFN support, support for stand-alone pages, Atom and RSS feeds for both content and comments, blogging API support (Atom Publishing Protocol, Blogger, MetaWeblog, and Movable Type APIs), spam blocking features, advanced cruft-free URL generation, a flexible theme system, and an advanced plugin API.
SugarCRM
SugarCRM is a complete CRM system for businesses of all sizes. Core CRM functionality includes sales force automation, marketing campaigns, support cases, project mgmt, calendaring and more. Built in PHP, supports MySQL and SQL Server.
Joomla
Joomla! is an award-winning Web-based content management system. It provides for split front end content access and backend administrator access. Group-based access control allows for different levels of system control for both the site and the administrator. The Joomla! framework allows for extension by installable components (applications), modules (template blocks), languages, templates, and mambots (plugins that enhance system functions).
