Online Timer — Free Countdown Timer with Alarm
Free online countdown timer with alarm: 1–60 minute presets or any hours, minutes and seconds. Stays accurate in background tabs, shows time in the tab title.
Convert in your browser · No sign-up
Timer ready
The remaining time is calculated from a fixed end time, so it stays correct even if this tab is in the background. Keep the tab open; the alarm plays in this page.
How to use
- Click a preset such as 5 min or 25 min, or type hours, minutes and seconds and press Set and start.
- Watch the large countdown (also shown in the browser tab title); pause, resume or reset at any time.
- When it reaches 0:00 an alarm tone plays; turn on browser notifications if you want an alert while working in another tab.
Example
Input: 0 h 12 min 30 s → Set and start Display: 12:30 counting down; tab title “12:29 · Online Timer”; alarm beeps at 0:00
Details and limitations
The alarm is generated with the Web Audio API in your browser, so no sound file is downloaded and nothing is sent to a server.
Browsers slow down timers in background tabs; this tool computes the remaining time from the end time instead of counting ticks, so it does not drift. Closing the tab or putting the computer to sleep stops the alarm.
FAQ
Will the timer still ring if I switch to another tab?
Yes, as long as the tab stays open. The countdown is based on its end time, and the alarm is scheduled for that moment. Turn on notifications to also get a system alert.
Why is there no sound?
Browsers only allow sound after you interact with the page, which starting the timer does. Check that the tab is not muted and use Test sound to check your volume.
How long can the countdown be?
Anything from 1 second up to 99 hours 59 minutes 59 seconds.
Related tools
Format references
Tool page updated: