IconVault's Pomodoro Timer runs the classic focus technique in your browser: 25-minute focus sessions broken up by short breaks and long breaks, with all durations editable to fit your rhythm. When a phase ends you get an audible beep and an optional browser notification, the timer advances automatically, and every finished session is saved to a session history you can review or export.

It is free and runs fully in your browser, with history stored on your device so no account is needed. The honest limit: the timer only keeps time while the page stays open, so closing the tab pauses your session. It tracks time in a box for you; it cannot make the work happen, but it gives focus a clear start and end.