How to use the online alarm clock
Setting an alarm for 12:21 am while everyone else is asleep can feel like cheating the clock, but it's usually just planning ahead for an early departure or a shift that starts before sunrise. This will sound at 12:21 am through your speakers, whether it's the depths of winter or a short summer night.
Choose a sound before you press Start — something like a chime or a classic bell tends to work better than anything too gentle. Once it's running, the countdown happens right here in the browser, which means the tab needs to stay open in the background rather than being closed.
The advantage of a browser alarm is volume and reliability at a desk: laptop speakers are often louder and easier to hear across a room than a phone left in a bag. The catch is that it depends entirely on the tab staying open; if the browser closes or the laptop sleeps, the alarm won't fire. On a 24-hour clock 12:21 am is written 00:21, and spoken aloud it's twenty-one minutes past twelve at night. Timetables and rosters may show it as 00:21, and handwritten notes as 12.21 am. If you need it loud, turn the system volume up before you start: the alarm plays at whatever the device is set to.
Common questions
What happens once the alarm goes off?
It rings through your device's speakers on a loop until you stop it from this page. There's no separate app notification, so make sure your volume is turned up before you rely on it.
Is this alarm accurate across daylight saving time?
It uses your device's local clock, so as long as your computer's time and date settings are correct, it'll adjust automatically when daylight saving time starts or ends.
Can I use this on my phone instead of a laptop?
Yes, it works in a mobile browser the same way, but phones are more likely to lock the screen or sleep, which can stop the alarm from ringing. A laptop or desktop tends to be more reliable for this.
Can I set more than one alarm at a time?
This page is built around a single alarm at a time. For multiple alarms, open a separate tab for each one and set a different time in each, keeping every tab open until it's rung.
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