If anyone actually needs a simple metronome that tracks time precisely using the Web Audio API, I built one recently: https://dkthehuman.com/metronome

- It's fast (the #1 metronome app on the iOS App Store taking 7+ seconds to start up on my iPhone was the reason I built this)

- It has keyboard shortcuts on desktop (use arrow keys to adjust BPM and space bar to toggle playing)

- It's a progressive web app so you can add it to your home screen and it'll behave like an app