Online Timer — Countdown, Stopwatch and Pomodoro
Countdown timer with alarm, stopwatch with laps and a Pomodoro timer, with a big fullscreen display.
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This online timer has three modes in one page: a countdown timer with an alarm, a stopwatch with laps, and a Pomodoro timer for focused work sessions. Pick a preset (1, 5, 10, 15 or 30 minutes) or type any time such as 7m30s or 1:30:00, press Start, and the remaining time shows in large digits and in the browser tab title, so you can see it from another tab. Fullscreen turns it into a classroom or meeting clock.
The timer keeps time from timestamps, not by counting ticks. Browsers slow down timers in background tabs, so a timer that counts one-second ticks falls behind when you switch away; this one compares the clock with the end time on every update and schedules the alarm for the exact end, so it finishes on time even if the tab was hidden. The alarm is generated in the browser with Web Audio and plays only after you have pressed Start at least once, because browsers block sound that a page starts on its own.
How to use
- Choose Countdown timer, Stopwatch or Pomodoro.
- For a countdown, click a preset or type a custom time (7m30s, 90s, 1h, 1:30:00, or a number of minutes) and press Set. Add a label if you like.
- Press Start or the Space bar. Pause, Reset or +1 min at any time; F toggles fullscreen.
- For the stopwatch, press Start, then Lap (or L) to record splits.
- For Pomodoro, adjust the focus, short break and long break lengths, then Start. Phases follow each other automatically unless you turn that off.
- Press Copy share link to send someone the same timer setup.
Frequently asked questions
Does the timer keep running if I switch tabs?
Yes. The timer stores its end time and works out the remaining time from the system clock, so it stays accurate when the tab is in the background. The tab title keeps showing the remaining time. Keep the tab open (closing it stops the timer) and keep your volume up so you hear the alarm.
Why did the alarm not make a sound?
Browsers only allow a page to play sound after you interact with it, so press Start (or Test sound) yourself rather than relying on a timer that started from a link. Check that Alarm sound is ticked, your volume is up and the tab is not muted. On iPhone and iPad the ring/silent switch also mutes web audio, so turn silent mode off.
What is the Pomodoro Technique?
A time-management method created by Francesco Cirillo in the late 1980s: work on one task for 25 minutes (one “pomodoro”), take a short break of about 5 minutes, and after four pomodoros take a longer break of 15 to 30 minutes. This timer follows that cycle by default and lets you change every length, for example 50/10 for longer focus blocks.
How do I share a timer with my class or team?
Set the timer up, then press Copy share link. The link stores the settings in the address, for example ?mode=timer&t=10m&label=Quiz, or ?mode=pomodoro&work=50&short=10&long=20&every=3. Whoever opens it gets the same timer, ready to start. Nothing about the link is stored on our side.
How accurate is the stopwatch?
It reads the system clock on every screen refresh and shows hundredths of a second. Accuracy is limited by your reaction time on the button far more than by the browser: for human timing, expect about a tenth of a second either way. It is not a substitute for electronic timing in competitions.
Why many browser timers drift, and how this one avoids it
The simple way to build a web timer is to subtract one second every time a one-second interval fires. That works while the tab is visible, but browsers deliberately slow timers in hidden tabs to save battery: Chrome, for instance, limits background timers to roughly once per second and can delay chains of timers in a tab hidden for several minutes to about once per minute. A counting timer then falls minutes behind.
This timer records the moment it should end and recalculates the remaining time from the system clock on each update, so a delayed update simply shows the correct, later value. A separate one-off timeout is aimed at the end time to trigger the alarm, which is not subject to the heaviest throttling because it is a single timer rather than a repeating chain. The stopwatch works the same way: it stores the start time and adds up completed runs.
Classroom and meeting uses
• Timed activities and tests: set the time, go fullscreen on the projector, and the digits stay readable from the back of the room.
• Presentations and stand-ups: one link per speaker slot (?t=3m&label=Updates) keeps everyone to time.
• Study sessions: Pomodoro mode with automatic phases means you do not have to restart the timer after every break.
• Choosing who goes next: pair it with the random name picker.
• Counting days instead of minutes, such as to an exam date, is a job for a date calculator.
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