The zetteldeft.org file in this repository contains documented code for a set of functions for emacs, which aim to extend the deft package and turn it into a (very very) basic Zettelkasten note-taking system.
Introduction, documentation, and code can be found in this single .org file here.
Or simply get the zetteldeft.el file and you’re good to go.
Want to read that in a more convenient format? Check it out on efls.github.io/zetteldeft.