Alarm / Reminder Timer

What it does

Set a time, and the page counts down to it. When it arrives, the countdown says Now, the page shows it plainly, and the chime sounds up to three times — unless you set it to silent first. A time that has already passed today is taken as tomorrow, which is what you meant.

It is one alarm at a time, deliberately: nothing to manage, nothing saved, and nothing to forget to delete.

When a browser tab will let you down

This is the part other pages leave out.

• The tab must stay open. Close it, and there is no alarm — this page cannot run in the background or send you a notification.
• A hidden tab may be throttled or frozen by the browser. The time will be right when you come back, but the chime may arrive late, or only on your return.
• A sleeping phone or laptop may suspend the page entirely, in which case nothing sounds until you wake it.
• The sound needs the page to have been touched, which pressing Set takes care of — but a muted device is still a muted device.

All of which is why the warning above the controls says what it says. For anything with a consequence, use the alarm built into your phone.

Keeping the screen awake

The toggle is off to start with. Turning it on asks your browser to stop the screen sleeping while the alarm is armed, which makes the alarm much more likely to fire on time — at the cost of a screen left on, which uses power and is not kind to an OLED panel over hours. It is your trade to make, so the page does not make it for you, and it says whether your browser actually granted it.

For a duration rather than a time of day, use the Countdown Timer; for work intervals, the Pomodoro Timer; and to watch the time itself, the Fullscreen Clock.