SilverStripe

vs

Bear CMS

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. 

Django CMS is a free and open-source content management system build on the Python web framework Django. With Django CMS, you can create your own website or blog in a matter of minutes which is easy to maintain far into the future. If you are a developer utilizing the Django framework you can integrate Django CMS into an exiting Django application and take advantage of it's publishing and editing features.

CMS Made Simple is a free and open-source content management system that offers an easy to use interface for end users, while maintaining a powerful backend for developers. CMS Made Simple is written in PHP and got an extensive API and custom modules. The CMS also utilize the Smarty templating engine that can be used to customize sites with HTML, CSS and PHP.

Fork CMS is a free and open-source, easy to use content management system built with PHP and Symfony Components. The content management system features an intuitive administration panel that makes it easy to create and manage content for the web. Fork CMS also comes packed with apps that can be installed to extend the feature set of the content management system.

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.

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.