Countdown Timer
Set a countdown timer with alarm online free — create timers for cooking, workouts, and events with sound alerts.
Last updated: 10 October 2026
Run a countdown with an audio alarm that fires at 00:00 — even when the tab is in the background, thanks to the Web Audio API. A 25-minute Pomodoro alarm triggered exactly on time; a 10-hour countdown showed no drift over the full duration.
Countdown Timer
Worked Examples
Tested timers
- 25-minute Pomodoro → alarm at exactly 00:00 via Web Audio API
- Alarm continues when the browser tab is backgrounded
- 10-hour countdown: display updates every second, no drift over the full run
Common presets
- Pomodoro: 25 minutes work, 5 minutes break.
- Exam practice: 45 or 90 minutes matching real paper lengths.
- Kitchen timing: multiple short runs — the timer resets without reloading.
About Countdown Timer
Set a countdown timer with an audio alarm. Enter hours, minutes, and seconds and start the countdown. An audio alarm plays when time expires. Test data: set a 25-minute Pomodoro timer — the alarm triggered exactly at 00:00 using the Web Audio API, which continued playing even when the browser tab was in the background. A 10-hour countdown also ran accurately with the display updating every second and no drift over the full duration.
Limits: No persistence — timer is lost if the tab or browser closes; Cannot customize the alarm sound; No visual notification or desktop alert — only audio; Very long timers (10+ hours) depend on the browser not discarding the background tab
Who Uses This Tool
- A developer using a 25-minute Pomodoro timer to focus on a coding task
- A cook setting a 45-minute timer for a roast and hearing the alarm from another room
- A student timing a 50-minute practice exam session with a clear end signal
Key Features
- Hours:Minutes:Seconds input
- Audio alarm via Web Audio API
- Works in background tabs
- Visual urgency indicator (flashing last 10 seconds)
- Pause and resume functionality
- Reset to clear timer
How to use Countdown Timer
- Enter hours, minutes, and seconds using the input fields.
- Click 'Start' to begin the countdown.
- The alarm sounds automatically when time reaches zero.
- Use 'Pause' to pause and 'Reset' to clear the timer.
How It Compares
Unlike online-stopwatch.com which requires staying on their page and shows ads, this tool runs in your browser tab with no data collection. The Web Audio API alarm is more reliable than JavaScript setTimeout alone, which can be throttled in background tabs.
Privacy & Security
Because processing happens directly in your browser, your files and input are not uploaded to our servers.
Written and checked by Mohammad Sohail
Alarm timing re-checked on 10 October 2026 with the 25-minute test run.
About FreeDigitalToolkit →Frequently Asked Questions
Does the alarm work if I switch tabs?
Yes. The alarm uses the Web Audio API, which plays audio even when the tab is in the background. You'll hear the alarm regardless of which tab is active.
Can I set a timer for more than 24 hours?
Yes. You can enter any combination of hours, minutes, and seconds. A 99:59:59 timer (just under 100 hours) works fine. However, very long timers depend on your browser keeping the tab alive.
What happens if my browser crashes or the tab closes?
The timer is lost — there's no way to resume a countdown after the tab closes or crashes. For critical timers, consider setting a system alarm as a backup.
How accurate is the timer?
The timer uses setInterval with drift correction, so it's accurate to within a fraction of a second over hours. The Web Audio API alarm fires precisely at 00:00.
Can I customize the alarm sound?
Currently the alarm uses a default tone. For custom sounds, you would need to modify the audio source in the code. The default tone is designed to be noticeable without being jarring.
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