What this timer does

Set a duration in hours, minutes, and seconds — or tap a quick-set like 5m or 25m — then press Start and the timer counts down to zero, where your chosen alarm sound plays until you dismiss it. You can also add alarm points that chime along the way: a recurring interval (a preset, or any minutes-and-seconds value down to the second) and one-off marks such as “when 1:00 remaining”. Press Fullscreen for a big standby display that reads like a wall clock across the room.

How it works

The countdown is timestamp-based, not a naive tick counter. When you start, it records the exact clock time it should end and, on every refresh, shows the difference between now and that moment. Because the remaining time is computed from real timestamps, it never drifts and stays accurate even when the browser slows the page down in a background tab.

The alarm sounds are generated in your browser with the Web Audio API — short tones synthesized from oscillators, not audio files downloaded from anywhere. You can set a separate tone for the interval chime, the one-off marks, and the final alarm, and Test each. Alarm points play as a single short chime, while the final alarm at zero repeats until you dismiss it. Browsers only allow sound after you interact with the page, so the first tone plays once you press Start or Test.

The fullscreen standby view uses your browser's Fullscreen API and, where supported, a screen wake lock so the display doesn't sleep while a countdown is on show. Press Esc or Exit to return.

Frequently asked questions

Is anything I do here uploaded or saved?

No. The timer and its alarm sounds run entirely in your browser. Nothing is uploaded, logged, or stored — the sounds are generated on your device on the fly, and reloading the page clears everything.

What are alarm points?

They're extra chimes before the timer ends. Set a recurring interval to chime every few minutes, and/or add one-off marks that fire once when a specific amount of time remains — handy for pacing a talk, a workout, or study blocks. The timer keeps running through them.

Does the timer keep running if I switch tabs or lock my phone?

Yes. Because the countdown is based on real clock timestamps, the remaining time is always correct when you return. Some browsers slow background tabs down, so the digits may only catch up — and the alarm may only sound — the moment the tab becomes active again.

Why does it show 0:00 or won't start?

The countdown needs a duration greater than zero. If hours, minutes, and seconds are all empty the display reads 0:00 and Start is disabled — set a time or tap a quick-set (for example 5m) and it will start.

How do I stop the alarm?

When the countdown reaches zero, press Dismiss (or Reset) to silence it. Leaving the page also stops the sound.

Does the screen stay on in fullscreen standby?

On browsers that support the Screen Wake Lock API, yes — the timer requests a wake lock so the display doesn't dim while shown fullscreen. Where the feature isn't available the timer still works; your device's normal screen-timeout settings apply.