Browser stopwatch with lap analysis and a separate countdown timer. Pause without losing state, save recent stopwatch records locally, and use an optional completion sound.
A quick decision brief for this specific tool
Stopwatch start/pause/reset and lap actions, or a countdown from 0–99 hours plus 0–59 minutes and seconds, with an optional completion sound
Elapsed stopwatch time, individual and cumulative laps, fastest/slowest/average laps, saved local records, or remaining countdown time and progress
The stopwatch derives elapsed time from performance.now(); the countdown derives remaining time from a target timestamp so delayed callbacks catch up while the page remains active
Choose your path
Measure elapsed time and manual laps or run one browser countdown without losing paused state when switching modes.
Record repeatable manual splits and compare pacing.
Start the stopwatch, record two or more laps, pause, and inspect individual/cumulative plus fastest/slowest/average values.
Can copy or print a reconciled lap list and understands device/browser latency limits.
Set an exact duration and receive a noncritical completion cue.
Switch to Countdown, enter integer hours/minutes/seconds, choose sound, and start or pause.
Zero duration cannot start, a one-second run ends at 00:00, and the user knows page closure, sleep, or policy can suppress the alert.
Keep selected stopwatch results without account sync.
Reset a nonzero stopwatch to save it locally, review up to 20 records, and explicitly confirm history clearing.
Understands records belong to this browser and destructive clearing does not happen from one accidental click.
This tool is part of these guided projects. Each project provides step-by-step instructions with checklists and all the tools you need in one place.
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Derives elapsed stopwatch time from performance.now() and renders hundredths of a second. The underlying clock is high resolution, but the displayed result remains subject to browser and device latency.
Records and displays split times with automatic lap numbering and duration calculation between laps.
Computes remaining time from a target timestamp, supports pause/resume, and can play an optional browser-generated tone when the open page observes completion.
Updated: August 2026
A coach uses the stopwatch to time athletes' sprints and record lap times for performance analysis.
A science student uses the timer to precisely measure reaction times and duration of chemical processes.
A home cook runs one countdown and keeps a separate safety-rated appliance timer as the authoritative alert when timing is critical.
Run a high-resolution browser stopwatch with laps or a target-time countdown. Modes preserve paused state, recent stopwatch resets can be saved locally, and the page clearly explains browser, sleep, and alert limits.
