Open Source Software for PHP
phpBB
One of the world most popular, free, open-source and self-hosted forum software, written in PHP. With phpBB you can create communities that can be hosted with most hosting providers. The software package is built and designed from the ground up to to be extensible and provides customization option through themes and feature extensions through plugins. The extensive database of user-created extensions and styles database, easy of use, and the simple installation process has made phpBB a common choice among self-hosted forums and communities.
MediaWiki
MediaWiki is a free and open source wiki engine used by thousands of organizations and websites across the globe. It's the software that powers Wikipedia, which was released as a free and open source project under the name MediaWiki, a year after the release of Wikipedia. The software allows people to collect and organize knowledge in cooperation with one another, and make it available on the web. MediaWiki is now built by a community of open source developers and provides plugins can be used to extend the software further. Allowing sister sites like Wiktionary, Wikimedia Commons and Wikidata to utilize the same code base.
Pydio
Pydio is an open-source and self-hosted file-sharing and synchronisation software that you can run on your own server. Pydio fits right into your data management policy, as it provides audit and reporting tools. With Pydio you can empower your organization by letting them control and manage content on the server while at the same time complying with the company security rules.
CodeIgniter
CodeIgniter is a powerful PHP framework with an extremly small footpring. The framework is built from the ground up to aid developers that want to build structured, secure and scalable web applications written in PHP. CodeIgniter is designed and developed at EllisLab and released as free and open source software under the MIT License.
phpMyAdmin
With phpMyAdmin you can manage MySQL and MariaDB via a user interface. phpMyAdmin is free and open-source portable web application written primarily in PHP. It supports wide range of native MySQL and MariaDB database operations including maniging tables, columns, relations, indexes, users, permissions and more.
CakePHP
CakePHP is a free and open source web framework for the programming language PHP. With CakePHP you can with ease, develop, deploy and maintain web applcations. CakePHP provides a sound structure that allow you to create organized applications that can scale and adapt as your project grows. Out of the box, CakePHP provides features like bake script, a rich query API, short RL syntax, database support for MySQL, SQLite, PostgreSQL, SQL Server, Oracle and more. It also includes features that make you app easier to develop such as automatic code generation, database migrations, fast and flexible templating language, and localization.
Flarum
A free and open-source modern forum software written in PHP. With Flarum you can eaisly setup your own discussion froum and host it online.
Simple Machines Forum
Simple Machines Forum or SMF in short is a free and open-source forum software. SMF can be used to build your own online community that you self-host on a host of your choice. Simple Machines Forum comes packed with features for customization, extension and management of your community. The template engine puts you in control of the design of your community. The plugin architecture makes it easy to extend and provide further feautres though third-party built packages.
PHP Microsite Boilerplate
PHP Microsite Boilerplate is a PHP framework to create simple, yet strongly functional, fast, and secure websites on basically every environment. PHP Microsite Boilerplate provides a simple starting block without installation of multiple dependencies and exhausting setup and configuration process. Allowing people to focus on building their website and simply host on cheap share hosting, cloud instances and hardware.
ProcessWire
With ProcessWire you can connect all your content seamlessly and making content management fast, easy and fun. ProcessWire is a free and open-source content management system and framework released under the Mozilla Public License 2.0. The CMS is built around an API wit similar naming connventions to that of jQuery, which makes it easier to use for JavaScript developers. It also provides a secure foundation, proven scalability and the performance needed to manage content online sucessfully.