Build a metronome app with time signatures, accents, tap tempo and practice ramps
A metronome has one non-negotiable: every click exactly on time. After that come the features musicians actually practise with: accents on the first beat, compound time, subdivisions, tap tempo and a gradual speed-up. Anticode can build a metronome app with all of these, its clicks synthesised in the browser and scheduled on the audio clock, and you can install it on your phone like any other app.
Accuracy first
Many simple online metronomes play each click from a JavaScript timer. Those timers are delayed whenever the browser is busy, so clicks arrive early or late by a few milliseconds, which trained ears hear as an uneven pulse. The reliable approach schedules each click a fraction of a second ahead on the browser's audio clock, which runs independently of the page.
Say this explicitly when you describe the app, then test it: run it at 60 BPM while scrolling and switching tabs, and listen for wobble. Record it with another device and look at the waveform if you want to be sure.
Metre, accents and subdivisions
| Setting | Example | Why it matters |
|---|---|---|
| Beats per bar | 2, 3, 4, 5, 7 | Odd metres for jazz, folk and progressive music |
| Beat unit | Quarter, eighth or dotted quarter | 6/8 felt in two needs a dotted-quarter beat |
| Accent pattern | Strong on 1, medium on 3; or 1, 4 in 6/8; or 3+2+2 in 7/8 | Lets the click show the phrase, not just the pulse |
| Subdivision | Eighths, triplets, sixteenths, swung eighths | Practising evenness inside the beat |
| Mute some bars | Two bars on, one bar silent | Builds internal time instead of leaning on the click |
Let each beat in the bar be tapped to cycle between accent, normal and silent. That one control covers most patterns without a menu.
Tap tempo and practice ramps
- Tap tempo. Average the last four taps, ignore a tap that's far off, reset after a pause.
- Tempo ramp. Start at 80, add 2 BPM every 4 bars up to 120. The classic way to work up a difficult passage.
- Practice timer. A simple count of minutes practised today, kept in the browser.
- Presets. Named settings for pieces ("Étude 3: 7/8, 3+2+2, 96") saved on the device.
- Tempo markings. Show Largo, Andante, Allegro beside the number for students.
Sound and display
Anticode's apps can't load sound files, so the click is synthesised with the browser's Web Audio API: a short sine or woodblock-like tone, higher for accents. Offer two or three click sounds, because a sound that cuts through a piano is harsh for a quiet guitar. Browsers only start audio after a tap, so the big Start button does double duty.
Visually, a pulse that flashes on each beat helps drummers and anyone practising with headphones off: a large beat number or a dot per beat lighting in turn, readable from a music stand. Honour reduced-motion settings with a gentler change rather than a flash.
Describing it to Anticode
"A practice metronome for music students. Tempo 30 to 250 with a big dial, plus and minus, and tap tempo. Beats per bar 1 to 12 and a beat unit, with each beat tappable for accent, normal or silent. Subdivisions: eighths, triplets, sixteenths, swing. A tempo ramp: start, end, step and bars per step. Mute bars. Named presets saved in the browser. Clicks synthesised and scheduled on the audio clock. Large beat display, dark stage-friendly theme, landscape on a tablet."
Once it's published, installing it puts it on a phone or tablet's home screen with an offline fallback, so it's there in a practice room without signal. Test it offline before you rely on it.
Limits
- No listening. There's no microphone access, so it can't detect your playing or tell you whether you're rushing.
- No sync with other devices or a band's in-ear system; each device keeps its own time.
- No backing tracks. Audio files can't load. For drum patterns rather than clicks, see the beat maker app.
- Silent mode. Some phones mute web audio when the ringer is off. Check yours.
Music teachers building a set of practice tools may also want an ear training app, and a music teacher website for lessons and enquiries.
Questions people ask
Is a browser metronome app accurate enough for practice?
Yes, if clicks are scheduled on the audio clock rather than with page timers. Ask for that and test it.
Can it do 6/8 properly?
Ask for a dotted-quarter beat unit with accents on 1 and 4, and an option to hear all six eighths.
Will my presets be on my other devices?
No. Presets are saved in the browser on that device.