Stopwatch & Timer

Why it stays accurate

Both timers measure when, not how often: the stopwatch records the moment you pressed start and adds up real elapsed time from the clock, and the countdown stores its end time the same way. Browsers slow down or pause page timers in background tabs — that makes a naive tick-counter drift or miss the end entirely. Here the alarm fires on time even if the tab sat in the background, and the display catches up the moment you come back.

The alarm beep needs one interaction with the page first (pressing start is enough) because browsers only let a page play sound after you have engaged with it — a sensible rule, kept here on purpose. No sounds play before the countdown reaches zero, and nothing is sent anywhere: the page has no network requests at all.