Flip Clock Timer

The timer counts down on the same split-flap cards as the clock, flipping only the digits that change. Eight presets cover the common cases — 1, 5, 10, 15, 25, 30, 45, and 60 minutes — and a custom form takes any hours, minutes, and seconds combination. Opening the page with ?m=25 preloads 25 minutes, so bookmarks and shared links start pre-set.

Accuracy comes from timestamps, not counters. Starting the timer records an end time; the display is recomputed from the system clock four times a second. Background tabs, throttled timers, and full page reloads cannot drift it — reopen the page mid-countdown and it resumes exactly where it should be. Pause stores the remaining milliseconds; +1 min extends the end time while running or paused.

At zero the stage pulses, a synthesised chime plays up to five times, and a browser notification appears if you enabled it. Three chime voices — Soft, Bell, Digital — are generated with the Web Audio API, so there are no audio files to download and the page works offline. The tab title shows the remaining time, which means a pinned tab doubles as a glanceable countdown.

Controls stay minimal on purpose: Space starts and pauses, R resets, F takes it fullscreen for classrooms, kitchens, gyms, and talks. Settings, presets, and chime options live outside the stage, so fullscreen shows only the cards. Like everything here, the timer is fully client-side — durations and preferences stay in this browser.