Recs.
Updated
A non-linear personal notebook used as a single HTML file in the browser or as a powerful Node.js application.
SpecsUpdate
Pros
Pro Progressive user level, from ease of use to programming your own plugins
Basic users can start with simple note-taking, progressively discover predefined features and existing plugins, then start using more fancy features (like filters, widgets, macros), in order to adapt their wiki to their needs.
Pro Lightweight and very customizable
Variety of settings, and community themes & plugins, available from built-in marketplace (CPL library). Every community plugin is open-source which means you can learn from it and develop your own. Some plugin don't require programming knowledge (written using WikiText), and is very easy to learn.
Cons
Recommendations
Comments
Flagged Pros + Cons
Pro Single html file
It's a single file and all your notes will be "accessible even in 25 years" because they can be seen in plain html text.