Open Source Software
Portal CMS
Portal CMS is a free and open source content management system with a powerful integrated page...
ExpressionEngine
ExpressionEngine is a flexible, feature-rich content management platform that empowers hundreds of thousands of individuals and organizations around the world to easily manage their web site. ExpressionEngine has a large community of developers that make add-ons that extend the system capability. With ExpressionEngine add-ons, no matter the task, you'll have a solution.
WordPress
WordPress powers roughly 30% of all web pages online. It's a free and open source CMS designed and developed for self-hosted publishing by Automattic, Inc. The software is written in PHP and utilize either MySQL or MariaDB as a database, and is compatible with most web hosts. Wordpress includes a plugin architecture and a templating system that can be used to extend and customize your website. These are commonly known as WordPress plugins and WordPress themes and make up a whole open source and commercial eco-system where anyone is free to create products for the platform.
Matrix CMS
Matrix CMS platform has been designed to provide a comprehensive and integrated solution to the product publishing requirements.
CMS Made Simple
CMS Made Simple is a free and open-source content management system that offers an easy to use interface for end users, while maintaining a powerful backend for developers. CMS Made Simple is written in PHP and got an extensive API and custom modules. The CMS also utilize the Smarty templating engine that can be used to customize sites with HTML, CSS and PHP.
PyroCMS
PyroCMS is a free and open-source Content Management System written in PHP on top the web development framework Laravel.
Drupal
Drupal is a free and open-source CMS written in PHP. Drupal is used for creating website for businesses, political parties and governments. The CMS currently powers 2% of all websites on the internet.
Pangea CMS
Pangea CMS is a powerful content management system designed for journalists. Pangea CMS provides a platform for quality and balanced journalism in 57 languages across 200 countries and territories around the world.
Batflat
Batflat is fast, database-less CMS written in PHP. Batflat weighs in on 1024 kilobytes and it has all features you have come to enjoy from other content management systems like WordPress. You can also download or create your own extensions for Batflat, allowing you to build features on top of the core and create unique experiences for the end-user.
Statamic
Statamic is a flat file based content management system written in PHP. With Statamic you can build better and faster websites that are easy to manage. Statamic features over 40 field types, drag & drop navigation builder, revision and content history, inline content editing, asset management, plugin architecture and real-time collaboration that makes content management a breeze.