Countdown Timer — Online Countdown with Alarm
Online countdown timer with duration presets or count-down-until-time mode. Plays an alarm when time runs out.
A drift-free countdown timer that runs entirely in your browser. Pick a duration in hours, minutes, and seconds, or count down until a specific date and time. Start, pause, and reset at will, and get an audible alarm the moment the clock hits zero. Presets for 5, 10, 15, and 30 minutes plus 1 and 2 hours make it quick to start a common timer.
A countdown timer is one of those tiny tools you reach for constantly: steeping tea, timing a workout interval, pacing a presentation, or marking a Pomodoro work block. This one runs entirely in the browser, so there's no ad interstitial, no signup, and no background sync to worry about.
The timing logic is drift-free. When you press Start, the tool stores the target end timestamp and reads the remaining time from the system clock on every animation frame. That means a 25 minute timer ends exactly 25 minutes later, even if the tab was backgrounded or your CPU stuttered. Pausing stashes the remaining milliseconds so resuming continues from the exact moment you stopped.
Two input modes cover both common scenarios. Duration mode accepts hours, minutes, and seconds for fixed intervals. Until-time mode accepts a datetime-local value for "count down to 3pm" style timers. When the timer reaches zero, the tool plays a 440Hz sine-wave beep for half a second through the Web Audio API and flashes a Time's up indicator. Presets for 5, 10, 15, 30 minute, 1 hour, and 2 hour start a fresh countdown with a single click.
- 1
Pick a mode and set the time
Use the Duration tab for a fixed interval (hours, minutes, seconds) or the Until tab to count down to a specific date and time.
- 2
Start the timer or use a preset
Press Start to begin, or click a preset button (5 min, 10 min, 30 min, 1 hour) to immediately launch a common duration.
- 3
Get an alarm at zero
When the countdown hits zero, the browser plays a beep and displays Time's up. Use Reset to clear the state and go again.
Pomodoro work blocks
Run 25 minute focus sessions followed by 5 minute breaks using the preset buttons.
Cooking and baking
Set a 10 or 15 minute oven timer without unlocking your phone or opening another tab.
Meeting and presentation pacing
Count down the remaining time for a standup segment, a lightning talk, or a timed interview answer.
Event countdowns
Use the Until mode to count down to a launch, deadline, or scheduled event at a specific clock time.
Will the timer keep running if I switch tabs?
Yes. The countdown is based on the actual end timestamp, not a ticking counter, so the remaining time is always accurate even if the tab was throttled or backgrounded while you were away.
Does the alarm sound play without a server?
Yes. The beep is generated in your browser using the Web Audio API (a 440Hz sine wave for 500ms). No audio file is downloaded and no network request is made.
Why didn't I hear the beep?
Browsers block audio until you interact with the page. Click Start at least once on the current tab and the alarm will play. Also check that your system volume is up and the tab isn't muted.
Is my timer data stored anywhere?
No. The timer runs in memory only. Refreshing the page or closing the tab clears the countdown. Nothing is uploaded, logged, or persisted.
How precise is the countdown?
Precision depends on the browser's animation frame rate, which is typically 60 frames per second. The end moment is accurate to within a few milliseconds of the target time.