Yon

“Yon is a little UI for knowledge designed to be used every day. Add your notes, write your diary, and connect thoughts with bidirectional links. Explore your text through an acme-inspired interface to dive deep or go wide and always find your way back. Yon code and your notes are contained in a single standalone html file with no dependency, so that you can open the lid and tweak any part of it and make it your own.”