Online Alarm Clock - Set an Alarm in Your Browser
Set an alarm for any time - morning wake-up, meeting reminder, or medication alert. Plays a sound alert right in your browser with optional desktop notifications. No app or download needed.
Set Alarm
Choose a time, sound, and repeat schedule. Keep this tab open so the browser can ring on time.
Alarm!
My Alarms
No alarms set. Use the form above to set your first alarm.
Tips for Reliable Browser Alarms
- Keep the tab open - the alarm runs in your browser, so the tab needs to stay open and active. If you prefer a duration-based alert, use the countdown timer instead.
- Turn up your volume - make sure your device is not muted or on silent mode.
- Disable "Do Not Disturb" - on mobile, DND can block browser audio even with volume up.
- Grant notification permission - click Allow when the browser asks, so you can get a notification even if the tab is in the background.
- Plug in your device - phones sometimes pause background tabs when on low battery.
How Browser Alarms Work
Time Checking with JavaScript
A browser alarm uses JavaScript's setInterval function to check the current time once per second (or more frequently). When the current time matches the alarm time you set, the alarm fires. This is different from a countdown timer - the alarm stores a specific target time and polls the clock until that moment arrives. The digital clock on this site uses the same browser time source to display the current time.
Sound via the Web Audio API
Alarm sounds are generated using the Web Audio API, which lets JavaScript synthesize tones, oscillations, and audio patterns directly in the browser without any audio files. This means no sound files need to be downloaded - the alarm tone is created on demand when the alarm triggers. You can test any sound before setting the alarm using the "Test Sound" button above.
Background Alerts via the Notifications API
When you grant notification permission, the browser can display a desktop notification even when the alarm tab is not the active one. This uses the browser's Notifications API - a separate channel from audio. On mobile, notification support varies by browser and operating system version, and the screen must not be suspended by battery-saver mode.
Scheduled Alarms vs Duration Timers
Not sure whether you need an alarm, a countdown timer, or a stopwatch? Here's how they compare:
| Feature | Alarm Clock | Countdown Timer | Stopwatch |
|---|---|---|---|
| Set by | Specific clock time | Duration (e.g. 20 minutes) | Not set - starts at zero |
| Works in background | Partial (tab must stay open) | Yes (JS continues) | Yes |
| Best for | Scheduled events, wake-up | Cooking, exercise, tasks | Measuring elapsed time |
| Repeating | Yes (daily repeat, snooze) | Yes (loop option) | Manual restart |
| Visual feedback | Current clock display | Countdown display | Count-up display |
| Sound | Alarm tone (selectable) | Alert beep | Optional lap beep |
Best Alarm Sounds and Wake Effectiveness
Not all alarm sounds are equally effective at waking a sleeping person. Research on auditory arousal thresholds shows that sharp, irregular sounds are more likely to penetrate deep sleep than gradual or melodic ones. The chart below reflects findings from sleep research studies on alarm sound effectiveness. For time-of-day awareness during your workday, the talking clock announces the current time aloud at regular intervals.
Wake effectiveness from deep sleep (approximate, varies with individual and sleep stage)
Best Reminder Use Cases
From morning wake-ups to professional reminders, a browser alarm is a lightweight solution for many time-sensitive situations. Here are the most common use cases and how to configure this alarm for each one. For recurring structured breaks at work, the Pomodoro timer automates the work/break cycle with audio cues.
| Use Case | Set Alarm For | Recommended Setup |
|---|---|---|
| Morning wake-up | Desired wake time | Classic Alarm + Repeat Daily; use as backup to phone |
| End of lunch break | Return-to-desk time | Bell sound, label "Back to work" |
| Medication reminder | Scheduled dose time | Repeat daily, label "Take medication" |
| Meeting start | 5 minutes before meeting | Chime, label "Meeting in 5 min" |
| Parking meter expiry | 10 min before expiry | Loud beep, label "Move the car!" |
| Power nap | Nap start + 20 minutes | Gentle tone; or use countdown timer instead |
Frequently Asked Questions
Will the alarm work if my screen turns off?
On most desktops and laptops, yes - the browser continues running in the background when the screen sleeps, and the alarm will fire. On mobile devices, the browser tab is typically paused or terminated when the screen locks to save battery, which means the alarm may not sound. For mobile wake-up alarms, your phone's built-in clock app is more reliable.
Will the alarm work if I close the tab?
No - this is a browser-based alarm. The tab must remain open. If you close the browser or the tab, the alarm will not fire. For a true background alarm, use your device's built-in clock app. This alarm is best used as a desktop reminder while you are already working.
Can I set multiple alarms?
Yes. Set an alarm, then set another one. All active alarms appear in the "My Alarms" section above and can be toggled on or off, or deleted individually. You can have as many simultaneous alarms as you need.
Can I choose different alarm sounds?
Yes. Use the sound selector to choose from Classic Alarm, Bell, Chime, Beep, or Gentle Tone. Each sound is generated by the Web Audio API and plays immediately in your browser. Use the "Test Sound" button to preview before setting the alarm.
Does the alarm work on tablets and phones?
The alarm can be set on any modern mobile browser and will play a sound when the tab is active and the screen is on. Results are less reliable when the screen is off or the app is in the background, due to how mobile operating systems manage battery usage. For critical alerts, combine this with your device's native alarm app.