Pick an alarm time, click Set alarm, and watch for the on-screen alert - Clear alarm cancels it.
Online Alarm Clock
FreetoolOnline editorial teamThis alarm clock runs entirely in your browser: pick a time, click Set alarm, and a bold on-screen message appears the moment the clock reaches it. There is nothing to download, install, or sign up for.
Because it is driven by your browser's own clock and not a server or a background service, you can watch the current time and set the alarm from the same screen.
Key features
- A live readout of the current time in HH:MM:SS format with today's date, updating continuously.
- Set alarm reads the time field and shows a confirmation line; Clear alarm cancels the alarm and resets the status back to "No alarm set."
- A bold on-screen "Alarm!" message the instant the browser's clock reaches the time you set.
- All timing runs locally on your device's clock - no upload, no account, and no tracking.
When to use it
Use it for things like a short reminder while you are already at the computer, a wake-up check during a nap, or a cue to switch tasks at a set time - anywhere a visual, on-screen alert is enough and you do not need a phone-style push notification.
How the alarm fires
The alarm does not play a sound or send a system notification when it fires - watch the tab for the on-screen "Alarm!" message. The tab also has to stay open: closing it or navigating away stops the check, since there is no background process keeping it running.
Related timing tools
Prefer a countdown instead of a fixed time, or just want to watch the clock without setting anything? These companion tools cover the neighbouring tasks:
| Countdown timer | Counts down from a duration you choose. |
| Digital clock | Shows the current time as a live digital display. |
| Analog clock | Shows the current time as a live analog display. |
Timing specifics worth knowing
A few timing specifics are worth knowing before you rely on this for anything precise. The clock re-reads your device's time every 250 milliseconds, so the visible HH:MM:SS readout stays smooth, but the alarm itself matches on the minute rather than the exact second - a target of 07:30 fires the instant the local clock rolls into 07:30, not at 07:30:00 to the second. Once it matches, a one-shot latch writes "Alarm! It is HH:MM now." exactly once and suppresses any repeat for the rest of that same minute, so you will not get a flood of duplicate messages while 07:30 is still on the clock. Because the comparison uses your own device clock and not a network time source, accuracy tracks whatever your operating system's clock and timezone are set to; a laptop whose clock has drifted will fire the alarm at the same wrong moment it shows on screen. There is also a hard tradeoff against a phone-style reminder: the Set alarm and Clear alarm buttons drive a plain setInterval loop with no background worker behind it, so the tab has to stay open and focused enough to keep running - close it or navigate away and the check stops until you set the alarm again. Setting a second time before the first fires simply replaces it, since only one alarm is tracked at a time.
Frequently Asked Questions
What does Online Alarm Clock do?
Lets you set an alarm time and shows a bold on-screen "Alarm!" message the moment the browser's clock reaches it, alongside a continuously updating current-time display.
Does it play a sound or send a notification when the alarm fires?
No - it shows an on-screen message only. There is no sound and no system notification, so keep the tab visible near the time you set.
Does the alarm still fire if I close the tab?
No. The alarm check runs only while the tab stays open - there is no background process, so closing the tab or navigating away stops it.
What complementary tools work well alongside online alarm clock?
The countdown timer counts down from a duration instead of a fixed time, and the digital clock and analog clock both show the current time as a live display if that is all you need.