Stopwatch
An online stopwatch with lap times, accurate in background tabs.
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How it works
Start the stopwatch and it counts up with millisecond precision. Rather than incrementing a counter that drifts when a tab is backgrounded, it records the real start timestamp and derives elapsed time from the system clock, so it stays accurate even if you switch away. Tap lap to record split times without stopping, and reset to clear. Everything runs locally in your browser — no account, no server.
Common use cases
- Timing a workout, run, or interval with lap splits.
- Measuring how long a task takes.
- Timing a presentation or speech rehearsal.
Frequently asked questions
Does it stay accurate in a background tab?
Yes. Elapsed time is derived from the real start timestamp against the system clock, so background-tab throttling does not slow it down. The correct time shows when you return.
Can it record lap times?
Yes. Tap lap while running to record a split; the list shows each lap's time and the cumulative total without stopping the clock.
Is anything saved to a server?
No. The stopwatch runs entirely in your browser. Times are gone once you reset or close the page.