Online Alarm Clock
Clean, simple web alarm clock with custom wake sounds, snooze, and quick presets.
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Important Reliability Note
This online alarm depends on your browser and device remaining active to run the page. Device sleep, computer shutdown, tab suspension, or aggressive OS power-saving modes may prevent the alarm sound from playing. For critical morning wake-ups, always use your smartphone or native device hardware alarm.
How to Use the Online Alarm Clock
Our free web alarm clock allows you to set custom wake times right in your browser. Choose your desired hour and minute using the digital time picker, add an optional label (such as "Meeting" or "Wake up"), and click Set Alarm. You can also click any of the quick-preset chips to advance your alarm by 5, 15, 30, or 60 minutes from the current time.
Wall-Clock Drift Free
Powered by authoritative system timestamps rather than simple interval counting, guaranteeing exact target synchronization.
Procedural Audio Alerts
Synthesized offline sound alerts via Web Audio API. Choose between Bell, Digital Beep, Chime, and Gentle tones.
Fullscreen Mode
Press F for a clean, full-screen digital clock that transforms any monitor into a desktop alarm display.
Keep Screen Awake
Optional Screen Wake Lock keeps your device display active while your alarm is scheduled so you never lose visibility.
Frequently Asked Questions
How does this online alarm clock calculate target times?
The alarm uses your device local timezone and authoritative wall-clock timestamps (Date.now()). If you set an alarm for a time that has already passed today, it automatically and safely schedules for that time tomorrow using calendar calculations.
Will the alarm sound play if my computer goes to sleep or is turned off?
No. Like all web browser applications, this page requires an active browser session to execute JavaScript and play sound. Device sleep, computer shutdown, or OS power-saving suspension will prevent the alarm from sounding. For vital wake-ups, always use your smartphone or native device hardware alarm.
Can I keep the screen awake while waiting for the alarm?
Yes. You can enable "Keep screen awake" in Settings. When supported by your browser, it utilizes the Screen Wake Lock API to prevent your display from dimming while the page is active.
How does the Snooze feature work?
Clicking "Snooze 5 Min" when the alarm rings immediately silences the sound and schedules a new alarm for exactly 5 minutes from the current moment.
Can I set an alarm using keyboard shortcuts or shareable links?
Yes. You can press Space to set or stop the alarm, and F to enter Fullscreen mode. You can also share or bookmark custom alarm times (for example, freetimertools.com/alarm-clock/?time=07:30).
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