Online Stopwatch & Countdown Timer
Track lap splits with millisecond precision or run custom countdown timers with audio alerts.
Recorded Laps
How to Use Online Stopwatch
- Choose 'Stopwatch' or 'Countdown Timer' tab.
- On Stopwatch: click 'Start' to begin timing, 'Lap' to record splits, and 'Reset' to clear.
- On Countdown: set hours, minutes, and seconds or click a preset button (1m, 5m, 25m Pomodoro).
- When countdown completes, a pleasant harmonic chime alerts you using the Web Audio API.
Technical Specifications & How It Works
High-precision timing uses the browser performance.now() monotonic clock, unaffected by system clock adjustments or drift.
Audio alerts are synthesized dynamically using the HTML5 Web Audio API with zero external audio media files.
Executes entirely client-side with full offline and background tab reliability.
Frequently Asked Questions
Is the stopwatch accurate down to milliseconds?
Yes, the timer measures elapsed time via window.performance.now() with microsecond resolution.
Does the countdown timer play sound when the tab is hidden?
Yes, the synthesized Web Audio chime triggers automatically when the countdown reaches zero even if the tab is in the background.
What is the 25-minute Pomodoro preset?
The Pomodoro Technique is a time-management method that breaks work into focused 25-minute intervals separated by short breaks.