Free and Open Source Software
FeinCMS
FeinCMS is a bare bones content management system written in Python on-top of the web framework Django. The CMS is built to know nothing about your content, and includes an admin interfaces that can handle content types. It lets you reorder page content blocks using a drag-drop interface, and you can add as many content blocks to a region (sidebar, header, etc) as you want. FeinCMS was built this way to allow for maximum flexibility, where developers, designers and content managers can create a unique site, tailored for their type of content and future patterns.
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.
Mixcore CMS
Mixcore CMS is an Open Source Enterprise ASP.NET Core / Dotnet Core CMS for building amazing digital experiences. It's made by a dedicated community. Anyone can use it, and it will always be free.
GeniXCMS
GeniXCMS is a Simple and Lightweight CMS and Framework. It's PHP Based CMS. Free and Opensource.
CouchCMS
With no knowledge of PHP required at all you can make any static web-page editable by your clients.
Agility CMS
Agility CMS is a cloud-based content management system for building and managing responsive websites and apps.
LightCMS
Easily Create Fantastic Websites with Highly Customizable Templates & Intuitive Tools for...
Flextype
Flextype is super fast headless content management system with an elegant architecture and built-in smart cache.