25 minute timer

A 25 minutes countdown — 25:00 — that starts the moment the page loads. It keeps time against your device’s clock rather than by counting ticks, so it stays accurate in a background tab, where browsers throttle timers to once a minute or less. Switch away and come back and it will be right.

The alarm is generated in the browser rather than downloaded, so there is no file to wait for. Browsers refuse to play sound until you have interacted with a page, so the first tap or key press arms it; the page says so while it is not yet armed rather than staying quiet at zero and leaving you to wonder.