倒數計時器

倒數計時與碼錶二合一，支援分圈。快速預設、超大數字，時間到可選提示音。完全離線運作。

Countdown Timer does two things and does them precisely: it counts down from whatever duration you type, and it counts up as a stopwatch that records lap times. Ninety seconds for a rinse, twelve minutes for a break in the oven, four hours twenty for a long errand — the number is yours to pick, every time. Both clocks are deadline-based rather than tick-based. A running countdown remembers the wall-clock instant it ends; a running stopwatch remembers the instant its current run began plus the milliseconds already banked. That means the popup can be closed, the tab throttled or a frame dropped and the clock still reads correctly the moment you look at it — nothing accumulates error. This is a general-purpose timer, not a session scheduler. There is no fixed sequence of intervals to follow, no task list and no statistics history: you enter a duration, it runs, it rings. The stopwatch side is for measuring things that have no set length at all — a run, a rehearsal, a support call, a set of reps — with laps and splits recorded as you go. Key features: - Time any duration you choose, from a single second up to 23:59:59, typed straight into an hours / minutes / seconds dial with start, pause, resume and reset controls - Switch to a stopwatch with lap times, each lap recorded to the centisecond next to its running total - Close the popup and keep counting, because the deadline is stored as a wall-clock instant — the timer and the stopwatch both show the true time when you reopen them - Jump to a common length with eight one-tap presets (1, 3, 5, 10, 15, 25, 45 and 60 minutes), and stretch a running timer with the "+1 minute" button at any moment - Hear a rising three-note chime when time is up, synthesized on the fly with WebAudio — there is no bundled audio file and no network request, and the tone repeats every 1.6 seconds until you press Stop or 90 seconds pass - Spot your fastest and slowest lap at a glance, colour-coded in the lap table as soon as you have recorded two laps that differ - Read a full-width progress bar and a large monospaced readout that switches to H:MM:SS past the hour, with a Ready / Running / Paused / Finished status line above it - Toggle the alarm off entirely, or on with a one-shot preview of the exact tone you will hear - Come back to a timer that expired while the popup was closed and still get its alarm, as long as it ran out within the last hour - Clear the lap list without resetting the stopwatch, or reset both together - Use the popup in any of 53 interface languages Privacy: everything is computed inside the popup with the browser's own clock and audio engine. The extension makes zero network requests, declares no host permissions, has no background page, never reads the pages you visit, and collects no analytics. Only your own timer settings stay behind, on your device.