Groovie

Groovie is a step sequencer and song timeline that runs as plain ES modules in the browser. No account, no backend, no framework. You sketch a pattern, arrange patterns on a timeline, then hit "Copy link". The project is encoded into the URL hash, so the link is the song. Nothing is uploaded.

Pattern length is in steps of fixed duration, not a fixed bar size, so a 15-step pattern and a 16-step pattern drift (free-running polymeters). It works on desktop and phones; the grid scrolls sideways on a narrow screen. MIDI clock goes out to hardware from the same scheduler that queues samples.

Maxime Chevalier-Boisvert split the code the way you would hope: model.js knows patterns and the URL codec and nothing about the DOM; audio.js is the Web Audio graph; view.js only reads. Tests in Node 22 lock the hash encoding against a corpus of songs so old links keep opening. A Claude Code skill in .claude/skills/make-a-beat writes a song file and emits a link through tools/make_song.js without uploading anything.

List it as a finished, remixable instrument. The hash codec is the product decision worth copying.