ionmetro

ionmetro is a precision metronome built for musicians who can't afford to be off the beat. Most metronome apps use a software timer to schedule clicks. Timers get pushed around by UI animations, scrolling, and background activity — and the beat drifts. ionmetro uses a look-ahead audio scheduler: every click is placed at a sample-accurate position in the audio buffer, 100 ms ahead of playback. The result is a rock-solid beat you can actually practice to. **Sample-accurate timing** Clicks are scheduled at the audio buffer level, not the UI thread. The tempo never drifts, even with your screen locked or while using another app. **Tap tempo** Tap in time with a recording or a musician. ionmetro locks in from your most recent tap interval — no averaging lag, just instant feel. **Time signatures** 2/4, 3/4, 4/4, and 6/8. The downbeat is always accented so you can feel the start of every bar. **Subdivision** Quarter notes, eighth notes, or triplets. Subdivision clicks are softer than the main beat so the pulse stays clear. **Four sound presets** Classic, Wood, Digital, and Soft — from bright and snappy to warm and muted. **Plays in the background** ionmetro keeps beating when you lock your screen or switch apps. Pair it with a sheet music reader, a tuner, or a recording app without losing the click. **No friction** No subscriptions. No ads. No accounts. Open it, set your tempo, press Start.