Software
Strapi
Strapi is a free and open source headless CMS developed with JavaScript for Node.js. The software makes it really simple to generate REST and GraphQL APIs. Simply create your database schema and relationships in the Strapi admin panel UI, and Strapi will auto-generate API endpoints to represent the data structures provided. Strapi comes packed with features you come to expect from normal CMS's such as authentication, authorization, content management and a media library. The software can be used for free and can be self-hosted on any server and platform. Extra enterpise functionallity is currently being developed, and will be sold at cost.
Textpattern
Textpattern is an elegant content management system that is free, open source software. Textpattern is designed to be flexible with powerful tag-based templates that allow you to structure data and manipulate content. The content management system itself can also be extended with the use of plugins, that allow anyone to improve core functionality or add new features. Textpattern already have hundreds of available community built plugins that can be used to improve your website today.
PhpSQLiteCMS
phpSQLiteCMS - a simple & lightweight CMS
Progress Sitefinity
Sitefinity's web content management software is a marketing command center to drive growth for your business. Easily manage multi-site experiences deployed your way.
Bear CMS
Bear CMS is a self-hosted content management system that seamlessly integrates with your website. With Bear CMS you own your data and content, which is store on your own server. Your websites and Bear CMS's management tools integrate seamlessly and creates an experience that content managers and editors will enjoy.
Storyblok
A headless & API-based CMS with an opt-in head and a visual editor. With Storyblok you can manage your content through an intuitive dashboard and access that data though the content delivery API, as nested JSON. Storyblok is an open-source software and can be used as such, but is also provided as a commercially hosted, cloud rendering service. As a front-end developer you can choose to work with any template engine, framework or system of your choice.
Kentico Kontent
Kentico Kontent is a leading provider of managed and headless content management systems. Kentico Kontent empowers enterprise business users and developers alike. The Modular content structure of Kentico Kontent frees developers to build any experience on top of their favorite tech stack. After the initial build, marketers can create new experiences and manage the components that appear across every channel.