OpenCMS

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govCMS

Sitecore A/S has produced the Sitecore content management system since 1999.

MODX is a free, open source content management system and digital experience platform. The CMS gives you full control over your creative, editorial vision and the experience you deliver. MODX is written in the programming language PHP and supports both MySQL and Microsoft SQL Server databases. The CMS is openly developed and released under the GPL license, and allows contribution.

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. 

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.

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.

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.