Open Source Software
Grav
Grav is a modern free and open source flat-file content management system. With Grav, you can publish content and build sites in a fast, flexible and simple manner with the file-based web platform. Grav requires zero installation and is just an zip archive that can be extracted to start using the CMS. Grave also comes with a powerful package management system that allow you to extend the feature set of Grav CMS. With the package management system you can install and upgrade themes and plugins written specifically for Grav. The software is written in PHP and released fully free and open-source under the MIT License.
Soosyze
Soosyze is a content management system without a database. With Soosyze It's easy to create and manage your website with little or no technical knowledge. The content management system is based on an MVC micro-framework in object-oriented PHP and on a noSQL library to ensure its stability and evolution.
Backdrop CMS
Backdrop is a full-featured content management system written in PHP. The Backdrop CMS allows non-technical users to manage a wide variety of content. It can be used to create all kinds of websites including blogs, image galleries, social networks, intranets, and more.
Automad
With Automad you can manage content easier than ever. Automad is a file-based content management and template engine that allow you to create fast website without the need of a database. Instead all content is stored in human readable text files which makes it easy to put a whole site under version control with Git. The elegant admin panel provided by Automad includes a block editor and the in-page editing capability. You can also extend the core of Automad by creating your own packages or making use of the once already created by the community.
Ghost
Ghost is a free and open-source headless CMS and blogging platform developed by Ghost Foundation. With Ghost you can manage content in style, the user experience provided by the software is intuitive and encourages writing. Ghost is written in JavaScript for the Node.js platform and is released under the MIT license.
Craft CMS
Craft CMS is a flexible, user-friendly CMS for creating custom digital experiences on the web and beyond. Craft is designed from the ground up to empoer the entire creative process. From the user-friendly interface to the completely customizable back end, everything you interact with is designed to just make sense. With Craft your content comes first. No more trying to make your content work within the confines of the CMS.
Directus
An open-source tool for managing content across all your omni-channel digital experiences. Directus is free and open-source headless CMS written in PHP, that takes a data first approach. Developers and content creators use Directus to manage content and generate a powerful API that can be used by any frontend technology. Directus can be self-hosted and is absolutely free.
Typemill
Typemill is an open-source flat-file CMS for content-driven websites and micro-publishers. With Typemill you can create handbooks, documentations, manuals, web-novels, traditional websites, and blogs. The content management system features a theme a plugin architecture that can be used to further extend the look and capaility.
Netlify CMS
Netlify CMS is a static site generator that is based on client-side JavaScript with a reusable APIs and prebuilt Markup. Simply pull in Netlify CMS to /admin of you site and you have an SPA (Single Page Application) admin panel that can edit content stored in a Git repository. Serving applications like this, the JAMstack way, improves performance, lowers cost of scaling and provides for a better development experience.
FireCMS
A free and open-source, firestore-based, headless content management system. WIth FireCMS can manage content through an intuetive admin panel that generate CRUD views based on your configuration. FireCMS is built with Typescript, Firebase, React + React Router, Material UI, Formik + Yup and aims to increase productivity for both developers and administrators managing content.