DocMGR - DocMGR is a complete, web-based Document Management System (DMS).
ClassicPress - The WordPress fork. No Gutenberg. Great future!
Novius OS - Novius OS is a Cross-Channel Open Source content management system (CMS).
Sitecake - Drag and drop CMS for HTML websites. It's flat file CMS so it's pretty fast.
MS SharePoint - Share, organize, and discover information with Microsoft SharePoint. Learn about SharePoint Online, OneDrive for Business, and Apps for SharePoint
TYPO3 - TYPO3.com - Infos, SLAs, Extended Support Versions and more