Open Source Software
Revize CMS
Revize is a web-based content management software designed for municipalities.
CushyCMS
CushyCMS is a FREE hosted content management system that's actually easy to use, fast to setup and doesn't require programming skills.
FrontAid CMS
FrontAid CMS is a decoupled and Git-based content management system. Content is stored in your own Git repository in the JSON text format. It works with all your current tools and you always own your data.
Anchor CMS
Anchor is a super-simple, lightweight blog system written in PHP. Compressed, Anchor CMS weighs in at just under 250kb making it an extremely light weight content management system. With Anchor CMS, you can manage content in HTML or Markdown, depending on which you prefer. The content management is fully free and open-source and released under the GPL-3.0 License.
October CMS
October is a free, open-source and self-hosted content management system written in PHP on top of the framework Laravel. The CMS features a universal extendable dashboard, inspector, reusable CMS components and a plugin system that can be used to extend functinality of your website. The plugin store contains thousands of community-made plugins that can either be purchased or installed for free. As a data store, October CMS supports MySQL, PostgreSQL and SQLite.
Flextype
Flextype is super fast headless content management system with an elegant architecture and built-in smart cache.
LightCMS
Easily Create Fantastic Websites with Highly Customizable Templates & Intuitive Tools for...
Subrion
Subrion is a PHP/MySQL based CMS & framework that allows you to build websites for any purpose. Yes, from blog to corporate mega portal.