Song Offset Listener

Offset Listener

Offset Listener is a phone app that lines up music across several phones. It is for people who want a room of phones to play one song in step.

Listen identifies the playing song by microphone and works out the playback offset. Search finds a track, and broadcast shares a sync anchor so other phones play in step. Nudge buttons shift the offset. Watch in sync, measure sync by microphone, and a live positions list help line phones up. The server side also looks up tempo, keeps a saved song index, and picks songs by genre, decade, and tempo for the lyric smash app.

Live at offset-listener.vercel.app.

This app is checked every morning by Control Troll.

Latest change. 2026-10-25, v2026.10.25. Added loudness maps for instrumentals, made on the phones. Saved song picks now accept any genre.

Full history is in CHANGELOG.md.