Online Alarm Clock

How this alarm clock works

The Sikelia Alarm Clock operates entirely within your browser tab using browser timers and Web Audio synthesis. It requires no background downloads or remote media assets. Simply leave the browser tab open for the alarm to sound on schedule.

Honest limitations

This alarm runs only inside this browser tab. Browser tabs throttle or suspend timers and audio in the background, so the alarm is not guaranteed to sound on time — or at all — while the tab is hidden, minimized, or closed. It cannot wake a sleeping device or ring like a phone or desktop OS alarm: that is operating-system behaviour no web page can provide. If the alarm's time passes while the tab is closed, the missed alarm is not replayed when you return.

Optionally, if your browser supports the Screen Wake Lock API, you can ask it to keep the screen on while an alarm is armed and this tab is visible. That only keeps the display awake — it does not make the alarm run in the background. Your alarm settings are saved in this browser only and never leave your device.