Online Alarm Clock: Step-by-Step Guide

The Online Alarm Clock tool lets you pick a time and shows a bold on-screen alert the moment the browser's clock reaches it. This guide covers how to set the alarm, what Set alarm and Clear alarm actually do, and what to expect - and not expect - when the alarm fires.

Last reviewed: 2026-07-18

freetoolonline.com Editorial Team

Setting the alarm

Setting the alarm uses your browser's native time picker on Alarm Clock - type the hour and minute or use the clock icon, then press Set alarm.

What Set alarm and Clear alarm do

Set alarm reads whatever time is currently in the field and stores it as the target; setting a new time before the alarm fires replaces the old target rather than adding a second one. Clear alarm cancels the stored target, resets the status line back to "No alarm set.", and clears any alert message that was showing. The live time readout above the controls keeps ticking the whole time, whether or not an alarm is set.

Setting	Range / value	Notes
Alarm time	00:00-23:59	24-hour time picked from the native browser time input
Active alarms	1 at a time	Setting a new time replaces the previous target
Check interval	Every 250 milliseconds	How often the page compares the live clock to the target
Alert repeat	Once	The "Alarm!" message shows once per fire, not repeatedly for the rest of the minute

What happens when the alarm fires

What happens when the alarm fires is a bold on-page "Alarm! It is HH:MM now." message under the controls on Alarm Clock the moment the live clock hour and minute match your set time - that is the only signal.

Alarm clock vs. the other clock and timer tools

The alarm clock fires at a fixed clock time you choose. The companion countdown timer instead counts down from a duration (minutes and seconds) rather than a time of day, and the digital clock and analog clock simply show the current time with no alert at all. Use the alarm clock when you care about a specific time; use the countdown timer when you care about how much time is left; use the plain clocks when you just want to check the time.

Common uses

Common uses for this browser Alarm Clock include a short desk reminder, a nap wake-up check, and a cue to switch tasks - without installing another app.

What this tool does not do

What this tool does not do: it will not ring if the tab is closed or sleeping, it is not a phone alarm, and it does not sync across devices.

Privacy

Privacy for Alarm Clock: the page runs in your browser tab using your device clock - nothing is uploaded and no account is required.

Companion tools

Companion tools next to Alarm Clock include the analog clock and countdown timer pages when you need a face clock or a timed countdown instead of a set-time alarm.

• Online Alarm Clock - the tool itself.
• Countdown Timer Online - counts down from a duration instead of firing at a fixed time.
• Digital Clock Online - a large live HH:MM:SS readout of the current time, with no alarm.
• Analog Clock Online - the same live time as a sweeping clock face.
• Utility tools hub - the rest of the everyday conversion and generator tools on this site.

Frequently asked questions

Does the alarm make a sound when it fires?

No. It only shows an on-screen "Alarm!" message - there is no beep, chime, vibration, or system notification.

Can I set more than one alarm at the same time?

Not on a single instance of this page - setting a new alarm time replaces the previous target. Open the page in a second tab or window if you need two independent alarms.

Does the alarm still fire if I close the tab or the browser?

No. The check only runs while this tab stays open - there is no background process, so closing the tab or the browser stops it completely.

How accurate is the alarm time?

It compares against your device's own local clock, checked every 250 milliseconds, so it fires within about a quarter-second of the target minute as long as the tab stays open and active. There is no sync to an external time server, so overall accuracy is only as good as your device's clock and timezone setting.