OnKey

OnKey is a free, open-source Mac singing coach for people who can't sing (yet). Play a song from Spotify, Apple Music or YouTube in your browser, and OnKey listens once to learn the original melody — it never saves the music. Then sing along: a scrolling note lane shows the target pitch while your live pitch curve is drawn over it (green means you're on it), each line gets scored, and you get a report at the end.

The tech runs entirely on your machine: a vocal-separation model isolates the melody, CREPE tracks pitch and the GAME note model turns it into the note lane. There is no account; the music you play and your voice never leave your Mac — network calls are limited to a short audio fingerprint to identify the song, a lyrics lookup, and update checks. It also handles low-octave singing as correct, works with any song, and is a native Apple Silicon app (M1 or later, macOS 14.2+).

The author, dsmurrell, tells the origin story in his Show HN post (2026-10-22): "So, I asked an agent (Claude Code) if it could write some code to listen to Spotify and also listen to me and see if it could detect both pitches and score me. It impressed me by writing some Python and showing me my pitch in the terminal!" That prototype became OnKey — free to use, MIT licensed, 247 stars on GitHub, actively pushed (2026-10-23). The site hosts a demo video of the author himself singing through it.