25 Minute Timer
Set for 25 minutes. Press start — it rings when the time is up.
This timer runs while the tab is open. If you need it to go off when your phone is in your pocket — that part needs the app.
Where the pomodoro’s 25 minutes came from
The number is not the result of research. In the late 1980s a student named Francesco Cirillo used a tomato-shaped kitchen timer to force himself through revision, and twenty-five minutes was simply what he settled on. The technique took the shape of the kitchen tool that happened to be on the desk.
That is worth knowing, because people treat 25 as if it were a measured optimum and then feel they are doing it wrong when it does not fit their work. Some tasks need ten minutes of momentum; some collapse if you interrupt them at twenty-five. The valuable part of the method was never the number — it was deciding the length before you start, so the decision is not made later by whatever distracts you.
If twenty-five works, keep it. If it does not, the honest version of the technique is to pick your own interval and defend it just as strictly.