XY Music Notation

XY Music Notation is a working answer to a niche musician's itch: what if sheet music were written for a base-12 world? The site renders full scores — Satie's Gymnopedie No. 1, Clair de Lune, Fur Elise, the Moonlight Sonata, Chopin nocturnes — in a custom notation where every note in 12-tone equal temperament is a number, N in (0,1,2,3,4,5,6,7,8,9,X,Y), with the pitch class printed right on the note head. The idea is to make the notation isomorphic to a new kind of music keyboard the author has been tinkering with, so you can sight-read a part by interval shape without decoding every note the traditional way.

The rendering engine is the clever bit: a music-score backend built on MuseScore with custom note heads that display each note's pitch class. The author built it with Codex — his own words on Hacker News: "I used codex to build a music score rendering backend based on MuseScore with custom note heads that display the pitch class of each note." He had been playing with the isomorphic keyboard himself and wanted real sheet music to practice on; the site is the tool he wished existed.

It is genuinely usable, not just a demo. Each score gets a playback bar with measure scrubbing, speed and volume controls, optional external MIDI output, PDF download, and a link to the original score — sources are marked cc-zero. Press play and follow along as the custom notation plays; click any note to preview that moment, click a rest to seek.

The Hacker News thread (83 points, 79 comments) turned into a lively debate about whether alternate notations help or hurt sight-reading, with guitarists and isomorphic-keyboard owners weighing in. Even the skeptics conceded the rendering itself is impressive. For musicians curious about notation beyond the staff, XY Music is a rare thing: a vibe-coded tool with real craft behind it.