Stopwatch & Timer

Every device has a clock, but when you want a precise stopwatch or countdown timer that works in your browser — without installing an app, signing in, or downloading yet another utility — the options thin out fast. This timer and stopwatch combination runs entirely in your browser with millisecond precision, supports lap tracking, and continues counting when the tab is in the background.

The stopwatch is built for interval work. Start, pause, resume, lap, and reset are one keystroke each (spacebar to start/pause, L to lap, R to reset) so you keep your hands on the workout or whatever you're timing. Lap times record into a table with split and total time, and you can export laps as CSV or plain text. Precision goes to milliseconds, which matters for short intervals where a 0.1 second difference is meaningful.

The countdown timer handles the rest. Set hours, minutes, and seconds, pick an alarm sound (or go silent), and the timer counts down. A progress ring gives visual feedback, the remaining time appears in the tab title so you can monitor without switching tabs, and an audio or browser notification fires when time is up. For work routines like Pomodoro, set 25 minutes, hit start, work until the alarm, hit start again for a 5-minute break. Combined with keyboard shortcuts and background operation, this is a productivity tool you'll actually reach for.

Accurate browser timers rely on performance.now() which returns high-resolution monotonic time in milliseconds with sub-millisecond precision. This is preferred over Date.now() for stopwatch use because it's immune to system clock adjustments. Rendering is throttled via requestAnimationFrame so the display updates at the screen refresh rate (usually 60fps) without burning CPU, while the underlying time tracking remains accurate even if the display is paused.

Background tab operation is important. Modern browsers throttle timers in hidden tabs to reduce battery drain — setTimeout and setInterval callbacks fire less frequently when the tab loses focus. But performance.now() still advances correctly, so the stopwatch uses timestamp math on visibility change events to reconstruct elapsed time accurately. A stopwatch started at 0:00 that runs for 5 minutes in a hidden tab will read 5:00 when you return, not some throttled half-time.

The countdown timer uses the same approach: an end timestamp, visibility-change reconciliation, and a periodic display update. When the timer expires, the tool plays a chosen alarm sound via the Web Audio API (for reliable audio even when other tabs are playing) and fires a browser notification (with permission) so you know even if the tab is hidden. Tab-title updates let you see the remaining time without switching tabs. All state lives in localStorage optionally, so accidentally closing the tab doesn't lose your running timer if you reopen within a few seconds.

Phone stopwatches are fine for simple use but requires reaching for a device. OS built-in timers work but notifications can be unreliable on long running systems. Dedicated Pomodoro apps add features but require installation. This browser-based tool gives you a precise stopwatch, countdown timer, lap tracking, keyboard shortcuts, and tab-title updates — all client-side, no account, no install. It keeps accurate time even with tab throttling and plays reliable alarms. Ideal for work intervals, workouts, cooking, and any timing you need without reaching for another device.