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Stopwatch and timer with laps in browser. Use when timing tasks; for date spans use date-calculator. Input: button controls. Returns elapsed time. 100% client-side.
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A precision stopwatch/chronometer with Start, Stop, Lap, and Reset controls. Displays time in hours:minutes:seconds.centiseconds format. Tracks laps with individual lap times, highlights the best and slowest laps, and allows copying all lap times.
A quick-access stopwatch is useful for timing code execution, measuring UI performance, or any task requiring precise time measurement without leaving the browser.
This tool is part of the DevStackIO platform — a collection of free online developer tools from DevStackIO. Browse more free developer resources on DevStackIO.
Developers measuring task durations, QA testers timing user flows, athletes tracking workout intervals, and anyone who needs a precise stopwatch in the browser.
Click Start to begin the timer
Click Lap while running to record a lap time without stopping the timer
Click Stop to pause the timer at the current time
Click Reset to clear all time and lap data
The lap list shows individual lap times with BEST and SLOWEST indicators
Click Copy Laps to copy all lap times to your clipboard
Start → Lap at 5s → Lap at 12s → Stop at 15s → shows 3 lap timesUse to time a for-loop execution: start before loop, stop afterTrack API response times across multiple requests using lapsHow accurate is the timer?
It uses requestAnimationFrame which syncs with the display refresh rate (typically 60fps / ~16ms precision). For sub-millisecond timing, use performance.now() directly.
Does the timer continue when the tab is in the background?
The display may pause due to browser throttling, but accumulated time is tracked correctly when you return to the tab.
What do BEST and SLOWEST mean?
BEST highlights the fastest lap time and SLOWEST highlights the longest lap time in your current session.
Can I export lap data?
Click Copy Laps to copy all lap times to your clipboard in text format.
Authoritative specifications, standards, and in-depth reading for Chronometer.
00:00:00.00
Timing uses requestAnimationFrame for smooth, accurate updates.
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