@irimi1 TiddlyWiki works offline, and you can run it locally. I've been using it as my "Zettelkasten" for a while now. (It's also a very mature yet simple webapp that you can run as a local single-file quine, or as an easy-to-install NPM package — all notes are saved as readable text). Makes linking between notes very easy. Recommended if you want to try something simple and effective :)
Server run by the main developers of the project It is not focused on any particular niche interest - everyone is welcome as long as you follow our code of conduct!