Online Alarm Clock
Set a time and press Set alarm; it rings with the sound you choose while this page is open.
The alarm only rings while this page stays open in a browser tab on a computer or phone that is awake. If you need to be sure to wake up, also use your device's own alarm, or download the calendar alarm.
What this tool does
Choose the time, a label and a sound, and press Set alarm. A big clock shows the time and the alarm rings when it arrives, with a Stop and a Snooze button. A web page can only ring while it is open in a tab on a device that is awake, so keep the tab open, test the sound, and use your phone's own alarm for anything critical.
Watches the clock and plays an alarm sound when your time arrives.
Offers snooze, a test button and a downloadable calendar alarm.
How to use it
- Pick the alarm time and type a label.
- Choose a sound and volume, and press Test to hear it.
- Press Set alarm and leave the tab open.
- Press Stop or Snooze when it rings.
Why use this tool
Rings at the time you set with a digital beep, chime or rising siren, with a volume control, a label, snooze and a test button, and keeps the screen awake where the browser allows it. Sometimes you need a quick alarm on a computer: for a nap, a meeting, cooking or a study break. An online alarm needs no app, and a visible clock makes it easy to see what is set.
Why we built it
We built the alarm clock to be clear that it only rings while the page is open, and to offer a calendar alarm file as a back-up. Plan sleep with the sleep calculator and use the countdown timer for short intervals.
Related tools worth a look: the ICS File Generator.
Who this tool is for
- People who want a quick alarm on a computer
- Students timing breaks
- Cooks and parents with a short reminder
When to use it
- A nap or a short break at your desk.
- A reminder to join a meeting or leave the house.
- Timing cooking or study sessions.
- When you do not have your phone to hand.
How it works
The page checks the clock twice a second and starts a repeating sound pattern when the time passes. Sounds are made with the Web Audio API, so no files are loaded. The Screen Wake Lock API, where supported, keeps the screen on while the alarm is set.
The calendar download is an .ics file for the next occurrence of the time, with a built-in alarm. Import it into a calendar app, which can wake you even when this page is closed.
Browsers pause or throttle background tabs and phones lock their screens. Do not rely on this page alone to wake you up for anything important.
What you give it, and what you get back
| Item | Details |
|---|---|
| Time and label | The alarm time (24-hour or your locale's format) and an optional label. |
| Sound and volume | Digital beep, chime or siren; 5 to 100%. |
| Output | A ringing alarm with Stop and Snooze, and an optional .ics file. |
Issues you may run into
| What you see | Why it happens | What to do |
|---|---|---|
| No sound | The browser blocks audio until you interact with the page. | Press Set alarm or Test the sound once. |
| Did not ring | The tab was closed, or the computer slept. | Keep the tab open and the device awake. |
| The wrong time | The alarm uses your device's clock and time zone. | Check your system time. |
Assumptions and limitations
- Rings only while the page is open.
- One alarm at a time.
- Depends on your device and browser settings.
Frequently asked questions
Does the alarm work if I close the tab?
No. A web page can only ring while it is open. Download the calendar alarm for a back-up.
Will it ring if my computer is asleep?
No. The device must be awake.
Can I use it on my phone?
Yes, but phones lock the screen and may stop the page, so use the phone's own alarm for important wake-ups.
How do I snooze?
Press Snooze when it rings; it sets the alarm again for five minutes later.
Is anything sent to a server?
No. Everything runs in your browser and nothing leaves the page.