Online Alarm Clock

Local time: 02:02:07 AM · keep this tab open and your device awake

No alarms yet. Add one above — it rings until you dismiss it.

💡 Wake-lock tip: prevent your device from sleeping while you wait (display settings or a keep-awake utility). This tab must stay open for the alarm to ring — it re-fires instantly if the tab was merely in the background.

Need an alarm a fixed stretch from right now? The 10-minute timer starts counting the moment you click — no clock math needed.

Quick Answer

An online alarm clock is a browser-based alarm: pick a time, keep the tab open, and a loud repeating melody rings at that exact moment until you dismiss it. Our free version supports multiple labeled alarms, snooze of +5 or +9 minutes, and a test-sound button. Everything runs locally in your browser — no sign-up, no downloads, and it keeps working offline once loaded.

How It Works

1

Pick HH:MM in the time picker, add an optional label, and click Add alarm

2

Hit TEST SOUND once to confirm the melody is audible at your volume

3

Keep the tab open and your device awake until the alarm time

4

When it rings, press DISMISS to stop it — or Snooze +5 / +9 minutes

Key Facts

  • Set multiple alarms with optional labels (e.g. "Stand-up meeting")
  • Loud 3-note melody repeats until you press DISMISS
  • Snooze buttons add +5 or +9 minutes in one tap
  • TEST SOUND button previews the alarm tone instantly
  • Live "alarm in 8h 3m" countdown for the next ringing alarm
  • Timestamp-based timing stays accurate even if the tab is throttled
  • Alarms are saved in your browser via localStorage — reload and they persist
  • 100% client-side: no account, no server, works offline after load

Frequently Asked Questions

Will the alarm work if my laptop is closed or the tab is closed?

No. This is a browser alarm clock, not a system alarm: if the laptop is closed, asleep, or the tab is closed, it cannot ring. Keep this tab open and the device awake for it to fire. The alarm re-checks the time the instant you return to the tab, so a backgrounded tab still rings as soon as you come back — but a closed lid or closed tab means silence. For a hardware-backed alarm, use your phone's built-in clock app.

Can I set an alarm for 10 minutes from now?

Yes — enter a time roughly 10 minutes ahead of the current clock shown in the tool, or use our dedicated countdown instead: the 10-minute timer at practicalwebtools.com/other/time/10-minute-timer starts a countdown from the moment you click, so it is exact without doing any clock math.

Does it work offline?

Yes. Once the page has loaded, everything — timing, sound, and saving your alarms — happens locally in your browser. No server is contacted after load, so it keeps working with the network disconnected.

How loud is the alarm and can I test it first?

The alarm is a synthesized 3-note melody repeated at full system volume until you press DISMISS — how loud it sounds depends on your device volume. Use the TEST SOUND button to preview the exact tone before relying on it, so you know it is audible from where you will be.

Will my alarms still be there if I reload the page?

Yes. Alarms are stored in your browser's localStorage, so they survive reloads and browser restarts. They are stored only on your device — clearing site data removes them, and nothing is ever uploaded.