MultiKit

Online Timer: Countdown With an Alarm, Free and Full Screen

  • Free
  • No sign-up
  • Runs in your browser
  • Version 1.0.1
  • Last updated 2026-10-25
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A countdown timer that rings when the time is up. Set hours, minutes and seconds, or pick a preset such as 5 or 25 minutes, and leave the tab in the background: the time is shown in the tab title and the alarm still sounds.

05:00

Quick set:

Press Space to start or pause.

The time is measured with the browser's own high-resolution clock, so it stays correct while the page is in the background.

Everything you enter is processed in your browser and is never sent to a server.

How to use

  1. Enter the hours, minutes and seconds, or press a quick-set button such as 5 min or 25 min.
  2. Press Start (or Space). The display counts down. Press Pause to hold it and Resume to go on.
  3. Choose a sound, set the volume and press Test the sound to hear it before you start. Tick Keep ringing to repeat the alarm until you press Stop the alarm.
  4. Press Full screen to show the time large from across a room. The address keeps the length, such as ?t=300 for five minutes, so you can bookmark a timer.

Examples

0 h 5 min 0 s
→ 05:00 counting down to 00:00, then Time's up! with the alarm
The same as pressing the 5 min button.
1 h 30 min 0 s
→ 1:30:00
Times of an hour or more show the hour in front.
Address ending in ?t=1500
→ The timer opens set to 25:00
Handy for a work and rest routine with a 25-minute round.

How it works

The timer stores the moment it should end, taken from the browser’s high-resolution clock, and on every frame shows the difference between that moment and now. It does not subtract from a counter on each tick, which is how timers drift or slow down when a tab is in the background and the browser holds its timers back. A second, slower check runs on an interval as well, so the end is noticed even when the page is hidden and frames are not drawn. Pausing keeps the time that was left and sets a new end moment when you resume.

The alarm is made with the Web Audio API: a few short tones, a bell with a long fade, or a digital beep, with the volume you set. Nothing is downloaded. Browsers refuse to start sound until the person has interacted with the page, so the audio is switched on when you press Start or Test the sound. The time left is also put in the tab title, so you can see it from another tab.

The functions that turn the fields and the quick forms into a duration, and the display, are covered by tests. The running timer, the alarm and the full screen view are checked in a real browser.

Sources

Frequently asked questions

Does the timer keep running when I switch to another tab?
Yes. It works out the time left from the browser's own clock and the moment it should end, not by counting ticks, so a tab in the background cannot make it slow. The alarm sounds in the background too, as long as the page stays open and your browser allows sound.
Why did the alarm not ring?
Browsers only let a page make sound after you have clicked something on it. Pressing Start counts, so a timer you started will ring. If you opened a link with ?t= and never clicked, press Start first. Check that the volume is up and that the sound is not set to No sound.
How accurate is it?
It shows the time left to the second, rounded up, so 00:01 means up to one second. The end is judged by the high-resolution clock, so the error is a few milliseconds at most, not counting how fast your device wakes the page.
Can I run several timers at once?
One timer per page. Open the page in another tab for a second timer; each tab keeps its own.
Is anything sent to a server?
No. The timer and the sound run in your browser, and nothing you set leaves it.
What is the largest time?
99 hours, 59 minutes and 59 seconds.
Version history
  • 1.0.1 — Clarifies the search title with the tool's main task and whether it is free or runs online.
  • 1.0.0 — First release.

Last updated: