Online Alarm Clock

This sets an alarm that rings from inside the browser tab itself — pick a time, add a label so you know at a glance what it is for, and it fires a sound and an on-screen alert when the clock reaches it. A nine-minute snooze matches the interval most physical alarm clocks and phones use, so the habit carries over.

What keeps it ringing, and what stops it

A browser tab can only run code while it exists, so the alarm fires as long as the tab stays open — in the background, in another window, even minimised — but stops being possible the moment the tab is closed or the browser quits. That is a real limitation worth knowing before relying on it for anything that matters: a laptop that goes to sleep, or a tab closed by mistake, silently cancels the alarm with no warning.

Browsers also block audio from playing until you have interacted with the page at least once, which is why arming the alarm plays a short test beep immediately — that click is what unlocks audio for the actual alert later.

Desktop notifications as a backup

Allowing notifications when prompted means the alert can still reach you if you have switched to another tab or application, since a desktop notification appears outside the browser window itself. It does not help if the tab or browser has actually been closed — for anything you genuinely cannot miss, a phone alarm remains the more reliable choice.