Online alarm clock: how to set one that rings
An online alarm clock is an alarm that runs in a web page instead of an app on your phone. The AlarmPick online alarm clock lets you pick a time, a label and the days it repeats, then rings when your device reaches that time. This guide shows how to set it up, and what to check so it actually rings.
The short answer
- Open the alarm page and keep that tab open.
- Enter the time you want, in the local time of your device.
- Choose once, every day, or particular days.
- Press Enable sound and Test sound before you rely on the alarm.
- Add the alarm and leave the page running until it rings.
The one rule that matters: an alarm in a web page can ring only while the page is open and able to run. Closing the tab or the browser stops it.
What an online alarm clock really is
A web alarm stores a clock time and compares it with the clock on your device. AlarmPick does not ask a time server for the time. If your computer or phone clock is wrong, the alarm will be wrong too.
For a reference, the US site time.gov is labelled "Official U.S. Time" and says its clocks are corrected for network delay. It also shows how far your device clock is off. Comparing your device with a source like that is a quick way to check it.
Time zones are described as offsets from UTC. NIST states that UTC is based on International Atomic Time and calls it the standard used for all general timekeeping applications. A web alarm does not choose a time zone for you. It uses whatever local time your device shows.
Why your tab has to stay open
A page that counts time uses browser timers. The HTML Living Standard says timers do not run exactly on schedule: "This API does not guarantee that timers will run exactly on schedule." It adds that delays due to CPU load and other tasks are to be expected.
The same standard lets a browser wait longer to save power. It says a browser may pad timeouts as needed to optimize the power usage of the device.
That is one reason a web alarm can be late in a throttled page. AlarmPick cannot run after the page is gone, and it does not run in the background the way an installed clock app does.
Background tabs, minimized windows and locked screens
The same standard says a page has a visibility state of either "hidden" or "visible". It describes hidden as covering a minimized window, a tab in the background, or a system element that obscures the page.
For your alarm, this means:
| Situation | What to expect |
|---|---|
| Page open and visible | The alarm rings at the set time. |
| Tab in the background | It can ring, but the browser may delay the page. |
| Tab or browser closed | It cannot ring. |
| Phone screen off or page frozen by the system | It may not ring. |
AlarmPick checks the device clock again when you come back to the page. If the alarm time was no more than about a minute ago, it still rings. After that it does not ring late. It moves to the next time and shows that the last one was missed.
Why the sound might stay silent
Browsers can block sound that starts without your input. The W3C autoplay specification says most user agents have their own mechanisms to block autoplaying media, and that those mechanisms are implementation-specific. It also says a policy of "disallowed" means no media is allowed to autoplay, and that the policy could change after a user gesture.
In practice, click Enable sound and Test sound once after you open the page. That gesture gives the browser a reason to allow the alarm sound. Other things to check:
- Volume zero is muted. A muted alarm does not play, and the page says so.
- If the browser still blocks audio, the due alarm stays on screen without sound.
- Turn your device volume up and test the chosen sound before bedtime.
How to set an alarm with AlarmPick
- Open the online alarm clock.
- Enter a time and, if you like, a short label such as Wake up or Workout.
- Leave every day selected, pick particular days, or choose once.
- Choose a sound and a volume from 0 to 100.
- Press Enable sound, then Test sound, to confirm that you hear it.
- Press Add alarm. Keep the page open until it rings.
- When it rings, choose Dismiss to end it, Snooze to wait five minutes, or Stop sound to silence it while it stays on screen.
You can keep up to 50 alarms in one browser. Off keeps an alarm and stops it ringing. Delete removes it. Alarms are saved in this browser only, so clearing site data removes them, and nothing is copied to a server.
Worked example: a weekday alarm
Say you want a workout alarm at 6:30 on Monday, Wednesday and Friday.
- Enter 06:30 and the label Workout.
- Select Mon, Wed and Fri.
- Set the volume to 70 and press Test sound.
- Add the alarm.
On Sunday evening the page shows the next alarm as Monday 06:30. If you snooze it, it rings again five minutes later, at 06:35, and the alarm time itself does not change.
When a timer fits better
An alarm answers "what clock time?" A timer answers "how long from now?" If you want to be told after 25 minutes, use the online timer instead of working out the clock time yourself.
Frequently asked questions
Is an online alarm clock free?
AlarmPick's online alarm clock is free to use and needs no account.
Will it ring if I lock my phone?
It may not. A phone with the screen off or a page the system has frozen may not run it. Use the alarm built into your phone for anything important.
Does daylight saving time change my alarm?
The alarm follows the local time on your device. Daylight saving can skip or repeat a local hour. A time that does not exist is skipped, and a time that happens twice uses the moment the browser returns.
Why did my alarm say it was missed?
The page was not running at that time. If you return more than about a minute late, it does not ring. It moves to the next time.
Can two tabs ring at once?
If the site is open in more than one tab, the tabs try to let only one play the sound. This is not a perfect lock, so a rare overlap is possible. Keep a single alarm tab open.