What this does
Pick a clock time, give it a name if you want, and hit Set alarm. The big readout at the top shows your live local time ticking by the second. When the clock catches up to a time you armed, the card flashes, your label pops up, and a beep starts looping until you press Stop.
It’s a wall clock, not a stopwatch. A stopwatch measures how long something takes. This fires at a moment you choose, say 7:00 AM or 2:30 PM, the same way the alarm on your phone does.
You can stack several at once. Set 9:00 for the standup, 12:30 for lunch, and 4:45 to pack up, all sitting in one list. Each row has a Remove button when you no longer need it.
Setting one up
Three fields, then a button:
- Time. Type or click the hour and minute. The picker uses your system’s format, so it might show AM/PM or a 24-hour spinner depending on your OS.
- Label. Totally optional. “Take the cake out”, “call mom”, “meeting” - whatever you’ll recognize when it goes off.
- Set alarm. Adds it to the armed list, sorted by time.
Want AM/PM instead of 24-hour everywhere? Flip the “Show 12-hour time” checkbox. It changes how the live clock and every armed alarm read, without touching what you’ve already set.
How the timing works
Once per second the page reads your computer’s actual clock and compares the hour and minute against each armed alarm. The moment they match, that alarm fires. Because it leans on real system time instead of counting seconds by hand, a brief browser hiccup won’t make it drift. The trigger is keyed to the minute, so an alarm rings as its minute begins and won’t double-fire during it.
There’s a catch. Everything lives in the tab. Nothing is stored on a server, and nothing syncs to your phone. Close the page and your alarms vanish. They don’t survive a refresh either, so treat this as a session tool.
About the sound
The beep is generated live with the Web Audio API. No audio file downloads, and the browser stays silent until you’ve clicked something on the page first, which is the gesture browsers want before they’ll let a site make noise. Setting an alarm counts.
When it rings, a short 880 Hz tone repeats a few times a second until you hit Stop. The card also flashes the whole time, so even on a muted machine you get a clear visual cue.
Hearing nothing? The usual suspects: the tab is muted, system volume is down, or a locked-down work browser has blocked the audio context outright. The flash fires no matter what, as a backstop.
Keep the tab in front
One thing that trips people up: background tabs get throttled. To save battery, browsers slow timers in tabs you’ve switched away from, sometimes to once a minute. The comparison still runs off the real clock, so the right alarm fires eventually, but the beep can land late if the tab was buried. Keep this tab visible and unmuted for anything you can’t miss.
Sleep matters too. If your laptop sleeps or the screen locks, the page pauses entirely. A browser alarm is great for “ping me in an hour while I work,” less great as a wake-up call.
Common questions
Will it wake me up in the morning?
Risky as a sole alarm. If the laptop sleeps or the screen locks overnight, the tab stops running and won’t ring. For waking up, use a phone alarm and treat this as a backup at most.
Why didn’t I hear the beep?
Check that the tab isn’t muted and your volume is up. Browsers also block sound until you’ve interacted with the page, so setting at least one alarm unlocks audio for the session.
Can I set more than one alarm?
Yep. Arm as many as you like, each with its own time and label. They show up in a sorted list, and any one can be removed on its own.
Does it keep working if I switch tabs?
The check keeps running, but background throttling can delay the beep. Bring the tab forward and a missed alarm catches up. For reliability, leave it on screen.
Are my alarms saved anywhere?
Nope. There’s no account and nothing leaves your device. Refresh or close the tab and the list resets to empty.
Can I pick the alarm sound?
Not right now. It’s a single repeating tone built in the browser, chosen because it cuts through without needing any download. Press Stop to silence it.