What a 30 minute timer is for
Half an hour is the default block for almost everything: the meeting, the workout, the thing in the oven, the episode you said would be the last one.
What people set it for
- A meeting that is supposed to be half an hour
- Baking, roasting or slow-cooking stages
- A full workout or a long walk
- Screen-time limits for yourself or the children
How this timer behaves
The countdown is stored as the moment it should finish, not as a number being decremented, so switching tabs or minimising the window cannot make it run late, and pausing and resuming is exact. Through the final minute the readout and its ring turn red and pulse, giving you a warning before the alert rather than only at it.
It does not start on its own. The alarm is generated in your browser, and browsers keep audio silent until you interact with the page — so a timer that started by itself would be a timer that finished in silence. One tap on start is what makes the sound work.