FeinCMS

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Nucleus 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.

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.

Wagtail is a free and open-source CMS built on-top of Django and Python. The CMS is built by developers and for developers and provides a configuration-less solution to content management. Wagtail plays nicely with your existing tech, especially if that stack utilze Python and the Django web framework. Wagtail can be installed as a package in existing Django application and extends the Django Admin to be more suited for content management.

ButterCMS is a commercial headless content management system and content API. With ButterCMS you can quickly setup your very own headless CMS that supports In-browser editing. Where you can quickly find and filter your images and files, update and schedule content and serve you assets over a content delivery network.

Quanta is a free, open source Content Management Framework thought for programmers and used for the creation of new-generation websites and applications.

Exponent CMS is a notable free and open source content management system that contains its own independent modular software framework of enterprise level.