Sitecake - Drag and drop CMS for HTML websites. It's flat file CMS so it's pretty fast.
The Artling - The Artling is an all-in-one curated online artwork gallery that has been providing people from across the globe with unique designs.
ClassicPress - The WordPress fork. No Gutenberg. Great future!
Inkbunny - Helping furry artists and story-tellers share their work.
TYPO3 - TYPO3.com - Infos, SLAs, Extended Support Versions and more
Weasyl - Open-source social art gallery