Countdown Timer, Stopwatch & World Clock Online Free
Three timing utilities in one tab: a centisecond stopwatch with lap splits, a countdown timer with presets (1–60 min) and a Web Audio chime, and a world clock showing local plus five major timezones. Timing uses performance.now() and wall-clock end timestamps so results stay accurate even when background tabs throttle intervals. No install, no ads, no network — pure browser timing for workouts, cooking, exams and distributed teams.
Countdown Timer, Stopwatch & World Clock In-Browser Workspace
Input data or select files to begin. 100% private, client-side execution with zero server transmission.
How to Use Countdown Timer, Stopwatch & World Clock
- Step 1: Pick the Stopwatch, Countdown or World Clock tab.
- Step 2: Stopwatch: Start / Pause / Lap / Reset — laps show split and total.
- Step 3: Countdown: choose a minute preset or ± buttons, then Start.
- Step 4: When time hits zero a chime plays; Replay re-triggers the tone.
- Step 5: World Clock: switch zones or scan the multi-city grid.
About Countdown Timer, Stopwatch & World Clock
The stopwatch accumulates elapsed milliseconds as base + (performance.now() − start) inside requestAnimationFrame for sub-frame precision without setInterval drift; Pause freezes base, Lap snapshots the current elapsed into a list (split = lap − previous_lap). The countdown stores an absolute end timestamp (Date.now() + remaining) and each frame sets remaining = end − now; when ≤ 0 it stops, flags done and plays a short 880 Hz sine oscillator beeps via AudioContext (created on user gesture to satisfy autoplay policies). World clocks format the same Date with Intl timeZone options (America/New_York, Europe/London, Asia/Tokyo, Australia/Sydney, UTC) so DST is handled by the platform. A 1 s interval updates “now” for the clock view only — timing modes rely on rAF/timestamps instead of coarse timers. Cleanup cancels animation frames on unmount. Using wall-clock end times means a throttled background tab still shows the correct remaining time when foregrounded (browsers may delay frames while hidden, but end − now stays honest). Ideal for pomodoro-style focus, lap drills and checking overlapping hours with colleagues.
Frequently Asked Questions
Why does the timer stay accurate in a background tab?
It targets an absolute end timestamp (end − now) instead of counting missed interval ticks.
Can I set a timer longer than 60 minutes?
Presets and ± go up to 180 minutes; adjust the minute stepper for custom lengths.
No sound when the timer ends?
Browsers block audio until you interact — click Start on the page first; use Replay chime if autoplay was blocked.
Does world clock handle DST?
Yes — formatting uses the platform Intl time zone database.
Is timing data sent anywhere?
No — all timers are local to the tab.