TiddlyWiki

TiddlyWiki is a personal wiki notebook that keeps each note as a tiddler and can run from a single HTML file opened directly in a browser. Tiddlers link and tag freely instead of sitting in a fixed hierarchy, and plugins add a server mode, export formats, or task lists on top of the core.

People use it for research notes, meeting minutes, and personal knowledge bases, while teams run the server mode for shared notebooks.

Keeping it on your own storage means a lifetime of notes stays in files you own and back up with the rest of your documents, with no account and no subscription involved.