FireCMS

vs

PyroCMS

Primo is an all-in-one IDE, CMS, component library, and static site generator. With Primo you can build sites faster, add and manage content more easily, create an actual, usable component library, and publish a fast, secure, cheaply-hosted static site.

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.

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.

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 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. 

Joomla is a free and open-source content management system written in PHP. The CMS is built entirely by volunteers from all over the world and has a strong community that provide educational resources, and extensions.