Online Alarm Clock
Set an alarm for a specific time of day, with a fullscreen ringing display, snooze and a small set of alert sounds.
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How this tool works
Enter the time you want to be alerted at and press Arm. The alarm shows exactly when it will ring — today or tomorrow, whichever comes next — and counts down to that moment.
Pause suspends monitoring; Resume continues counting down to the same set time. If that time passed while paused, the alarm rings when you resume. Disarm cancels it and unlocks the time field for a new one. Once it rings, Snooze delays it by 9 minutes, and Dismiss turns it off.
Pick one of a small set of alert sounds and preview it at your chosen volume before arming — sound only ever plays after you've interacted with the page at least once, since browsers block audio otherwise.
Fullscreen mode enlarges the display for a room: a desk, a nightstand, a shared screen. It uses your browser's fullscreen feature where available; if that isn't supported, the large-display view still works without going edge-to-edge.
This page has to stay open on an awake device to ring. It is not a dependable alarm across a full device sleep, a closed browser, a terminated tab, or OS/browser throttling — nothing is saved, so closing or reloading the page cancels it.
Frequently asked questions
Will this ring if I switch tabs, close the tab, or my device sleeps?
Not reliably, and it depends on which of these happens — they're not the same. Backgrounding or minimizing the tab is the mildest case: the browser may suspend or throttle it enough that sound is delayed or simply missing when the target time arrives. Device sleep or a locked screen is less predictable still: whether the ring fires at all while asleep depends on the browser and operating system, not this page — nothing here can guarantee it either way. Closing or reloading the tab or browser is different again, not just less likely to ring — nothing about this alarm is saved, so it's cancelled outright: there's no state left and no alert that can fire. Separately from all of that, your browser blocking or restricting audio (a permission or autoplay setting, unrelated to backgrounding or sleep) can also mean sound doesn't play even while everything else is working normally. For the best chance of hearing the alert, keep this tab open and active, keep the device awake, and ensure sound is allowed. Backgrounding the tab may delay or prevent the alert. If you need a guaranteed wake-up, use your phone or a physical alarm clock as a backup.
Does the sound play automatically?
No. Browsers block audio until you've interacted with the page, so sound only ever plays after you've pressed Arm or Preview sound at least once in the current visit.
What happens if the time I set doesn't exist, or happens twice, because of a clock change?
It's disclosed, never guessed. If your chosen time falls in a daylight-saving spring-forward gap, the alarm is set for the next day that time actually occurs. If it falls during a fall-back, so the same clock time happens twice, the alarm is set for one specific occurrence and the page states which one and why.
What does Snooze do?
It stops the current ring and re-arms the alarm for 9 minutes later.
Can I set this to repeat every day?
Not in this version — each alarm is a one-time arm, not a recurring schedule. Set it again for the next time you need it.
How is this different from the Countdown Timer?
Countdown Timer counts down a duration you enter, like 25 minutes. This tool rings at a specific clock time you choose, like 7:00 AM, whether that's a few minutes away or most of a day away.
Is my alarm saved if I close the page?
No. Nothing is stored anywhere — closing or reloading the page cancels it.