Open Source Software for Self-Hosted
Squidex
Squidex is 100% open source headless CMS, built by passionated developers. With Squidex both individuals and organizations can handle content for the new web with ease. Squidex modular platform allows users to create content APIs that can be consumed by any frontend framework or technology in a matter of minutes. The framework itself can also be extended and tweaked to suite individual use-cases. Squidex is provided as a fully open source software released and free of charge, for the self-hosted community edition. For organizations that want to get up and running fast, commercially hosted solutions are provided.
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.
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.
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.
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.
Hugo
Hugo is one of the most popular open-source static site generators. With its amazing speed and flexibility, Hugo makes building websites fun again. Hugo is the fastest tool of its kind, it generates pages at <1 ms per page, the average site builds in less than a second. Hugo also supports unlimited content types, taxonomies, menus, dynamic API-driven content, and more, all without plugins. Hugo is written in Go and released fully free and open-source under the Apache-2.0 License.
Superdesk
Superdesk is a state-of-the-art digital newsroom system that combines headless CMS functionality with powerful workflow features for an end-to-end news creation, production, curation and distribution platform. With Superdesk you can create and distribute content to any platform. All within a web-based dashboard that share many similarities with a regular newsroom, while providing remote-friendly workflows that will make journalist feel right at home.