Sitecake - Drag and drop CMS for HTML websites. It's flat file CMS so it's pretty fast.
Novius OS - Novius OS is a Cross-Channel Open Source content management system (CMS).
ClassicPress - The WordPress fork. No Gutenberg. Great future!
DocMGR - DocMGR is a complete, web-based Document Management System (DMS).
TYPO3 - TYPO3.com - Infos, SLAs, Extended Support Versions and more
Freevo - Imagine a world where the tv guide is liquid, where the time slots are organised to suit your schedule.