Countdown Timer
Two timers in one. Set a duration and start it, or pick a date and watch the days tick down to it. The remaining time also appears in the browser tab title, so you can work in another window and still see it.
Read in your device's local time.
Why the countdown is accurate and the alarm still might not be
There are two ways to build a countdown. The naive one starts at a number and subtracts a second every time a timer fires. It drifts, because browser timers are not promises — under load, or with a busy tab, setInterval fires late and every late fire is lost time that never comes back.
This timer does the other thing. It stores the wall-clock instant you will reach zero and, several times a second, asks the clock how long is left. The display is therefore never wrong by more than a fraction of a second, no matter how badly the browser is behaving.
What that does not fix is when the alarm rings. Browsers deliberately slow down timers in tabs you are not looking at, usually to about once a second, and Chrome can cut them back much further — to roughly once a minute — after a tab has been hidden for several minutes. The remaining time stays correct because it is recomputed from the clock, but the moment the tool notices zero can arrive late. If your laptop went to sleep, the timer notices the instant it wakes, which can be hours after the fact.
The practical rule: for anything under a few minutes, keep the tab visible. For a long countdown, use it to watch the number rather than to be interrupted by it.
Nothing is saved
There is no account, no storage and no notification permission request. Close the tab or reload the page and the timer is gone — the settings do not come back. That is a deliberate trade for a tool that runs entirely on your device, but it makes this the wrong choice for a timer you need to survive a browser restart.
It also means only one timer runs at a time. If you need three parallel timers, open three tabs, and expect the hidden ones to be throttled hardest.
The sound
The alarm is three short tones generated by the Web Audio API, not an audio file, so nothing is downloaded and the page stays small. Browsers block sound that a visitor did not ask for, so the audio is unlocked by the click that starts the timer. That is also why the alarm can stay silent if you tick the sound box after starting.
Two things will mute it anyway: a tab muted from the browser's own tab menu, and, on an iPhone, the physical silent switch. Neither is something a web page can detect or override.
Counting down to a date
Date mode reads the date and time in your device's own zone and counts to that instant. A countdown to "1 January at 00:00" is therefore a countdown to midnight where you are, not midnight in New York or Sydney. If you need another zone, convert the time first and enter the result — there is no zone picker here.
Daylight saving is handled correctly, and it is worth knowing what "correctly" means. The countdown measures the real elapsed time to that instant, so a target three days away across a spring-forward change is 71 hours, not 72. The clock on your wall skipped an hour, and so does the countdown.
What this is not
It does not count up, so it is not a stopwatch. It does not repeat, so it will not run intervals for a workout. There is no way to label a timer, no history, and no way to be notified once you have closed the page. Those all need either persistence or notification permissions, and the moment a tool needs those, it stops being something that works with the tab closed and your data untouched.
Frequently asked questions
Does the timer keep running if I switch to another tab?
Yes. The remaining time is worked out from the clock rather than counted down, so it stays correct while the tab is hidden. What can slip is the alarm: browsers throttle background tabs, so the beep may land seconds or, after a long time hidden, minutes late.
Will it still run if I close the tab?
No. Nothing is stored and there is no notification permission, so closing the tab or reloading the page ends the timer. For anything you need to survive a restart, use your phone or your operating system.
Why did my alarm ring late?
Almost always a throttled background tab or a sleeping machine. The countdown notices zero only when the browser lets it run, and on wake it will fire immediately even if zero passed an hour ago.
Can I count down to a time in another time zone?
Not directly — the date you enter is read in your device zone. Convert the target time into your own zone first, then enter that. Anything else risks being an hour out twice a year.
Can I turn the sound off?
Untick "Sound at zero" and the timer finishes silently, leaving the message and the tab title as the only signal. Muting the tab in your browser works too, and takes priority over anything the page does.
Last updated September 19, 2026