30
TiddlyWiki: An Open Source Alternative to Notion or Obsidian
(thenewstack.io)
Logseq is also open source but it does have plugins, it's extensible, and was launched in the last 5 years, not 20.
The caveat is that it's more of a Roam alternative, so it works for the many people who use Obsidian/Notion as a powerful outliner, but it might fall a bit short as a wiki. I'd still favour it over TW though.
That's why I did not use Logseq at first, but tbh, I see bo problem in building a knowledge base with Logseq. It's working well for me.
I've been using TiddlyWiki for more years than I care to remember!
Does exactly what it says on the tin. Single file, portable or hostable.
I used it over a decade ago. Glad to see it's still true to its core and still alive
Konzepte, Methoden und Tools des pkm; deutschsprachig