Online Alarm Clock

How to set an alarm

1. Choose the Alarm time. The big clock at the top shows the current time of your device.
2. Optionally type a Label (for example “Wake up” or “Take the bread out”), choose a Repeat option (Once, Every day or Working days) and a Sound (Beeps, Bell or Digital).
3. Click Add alarm. The alarm appears in Your alarms with the time left before it rings, and the next alarm is shown under the clock and in the tab title.
4. When the alarm goes off, the sound plays for up to one minute and a banner shows its label. Click Stop, or Snooze 5 min to hear it again five minutes later.

Use the On checkbox to switch an alarm off without deleting it, and Delete to remove it. Click Test sound before going to sleep to check the Volume.

Important: keep the tab open and the device awake

This alarm clock runs inside a web page, so it has the same limits as any website:

• The tab must stay open. Closing the tab or the browser cancels every alarm until you open the page again.
• The device must stay awake. A computer in sleep or hibernation, or a phone that has suspended the browser, can’t play sound. On a laptop, plug it in and set it not to sleep; on a phone, keep the screen on and the page in front.
• The sound must be on. The alarm plays at your device’s volume, so check that it isn’t muted and that no headphones are connected.

Tick Keep the screen on while this page is open to ask the browser to prevent the screen from turning off (Screen Wake Lock API). Not every browser supports it, and a battery saver can refuse it; the tool tells you when that happens. For anything critical, such as catching a flight or taking medication, use your phone’s built-in alarm as well.

Saved alarms and sound

Your alarms are saved in this browser’s local storage, so they are still there the next time you open the page on the same device. Nothing is sent to a server. Browsers only allow a page to play sound after you interact with it: when you come back to the page with saved alarms, click Enable sound (or anywhere in the tool) so they can ring.

The sounds are synthesized by the Web Audio API, without any audio file. About a minute and a half before an alarm, its sound is scheduled on the browser’s audio clock, so it rings on time even if the browser slows down timers in a background tab. If the device was asleep at the alarm time, an alarm found less than ten minutes late still rings; after that, the tool shows that it was missed instead of ringing hours later.

Alarm times follow your device’s clock and time zone, including daylight saving time changes.