tiddlyroam is a free, open source alternative to Roam. It is a notetaking app that works the way your brain does: networked, personal and infinitely customisable: https://tiddlyroam.org/
From the commonplace book to the zettelkasten to the personal wiki, and everything in between. Technology-focused content and practice-based content both welcome. While we’re still small, screenshots of your notes that you’re particularly proud of are also welcome!