Alarm Clock Online — Free, Custom Sounds, Browser
Free online alarm clock — set time, custom sounds, snooze, fullscreen mode. Browser-only — no signup.
About Alarm Clock
A browser-based alarm clock runs in any tab and rings at a chosen time — useful when your phone is on silent, when you're at a desktop computer, or when you want a backup alarm visible on a separate screen. The ZTools Alarm Clock supports multiple alarms, custom sound choice (ten built-in tones plus upload-your-own), snooze, fullscreen display, and sticky tab notifications so the alarm fires even when the tab is in the background. Runs entirely client-side; no signup, no account.
Use cases
- Backup alarm at your desk. Phone on silent during a meeting; alarm clock in a browser tab catches you when the meeting runs over.
- Cooking / baking timer. Set an alarm for when bread comes out of the oven. More reliable than a kitchen timer that runs out of battery.
- Pomodoro reminder. 25 minutes work + 5 minutes break — set an alarm at the end of each cycle. Or use a dedicated Pomodoro timer.
- Wake-up alarm on a hotel laptop. No phone charger; laptop is your only device. Alarm clock in a browser tab works.
How it works
- Set time. Pick the alarm time. Multiple alarms supported.
- Pick sound. Built-in tones (gentle bell, classic ring, bird chirp, etc.) or upload your own MP3.
- Configure. Snooze duration (default 5 min), repeat (one-time or daily).
- Activate. Browser uses Web Audio API to play sound. Notification API surfaces a desktop notification when the alarm fires.
Examples
Input: Alarm at 7:30 AM, gentle bell, snooze 5 min
Output: Browser plays sound at 7:30. Snooze button delays by 5 min; second snooze re-triggers.
Input: Multi-alarm: 9:00, 12:00, 17:00 (workday milestones)
Output: All three trigger throughout the day. Each labelled.
Frequently asked questions
Will it ring if the tab is in the background?
Modern browsers throttle background tabs — alarms fire but with a few seconds delay. For mission-critical wakeups, keep the tab in the foreground or use your phone.
What if I close the tab?
Alarms don't persist past tab close. The tool isn't a daemon — it's a browser tab.
Notification permission?
Optional. Without it, alarm still fires sound; with it, you also get a desktop notification.
Privacy?
All in browser. Alarms / sounds never uploaded.
Pro tips
- For background reliability, keep the tab in the foreground — most browsers throttle non-foreground tabs.
- Custom sound? Upload an MP3 — the alarm uses your file via local URL, never uploads it anywhere.
- For Pomodoro, multiple alarms work — but a dedicated Pomodoro timer is more ergonomic.
- Don't rely on this for medication reminders or critical wake-ups — phone alarms are more robust.
Reviewed by Ahsan Mahmood · Last updated 2026-05-06 · Part of ZTools.
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