Set a time, press Start and this online timer counts down to zero, then sounds an alarm and flashes the screen. Pick a preset from 1 to 30 minutes or enter your own hours, minutes and seconds. It runs entirely in your browser: nothing to install, nothing stored or sent.
How it works
When you press Start, the timer notes the exact moment it should end: the current clock time plus the duration you set. Every time the display refreshes, it subtracts the current time from that end point, so the remaining time is always measured against the clock instead of being counted tick by tick. That matters because browsers slow down timers in background tabs, often to one update per second or less, to save battery. A timer that counted its own ticks would fall behind; this one reads the clock again on its next update and shows the right remaining time, so it finishes on time even if you switch tabs. The tab title shows the remaining time as well, so you can follow it from another tab. The alarm is a tone generated in your browser with the Web Audio API, so no sound file is downloaded. Browsers only let a page play sound after you interact with it, which is why the Start click also unlocks the audio. Pause freezes the remaining time and Resume picks it up again; Reset goes back to the time you set.
Worked example
For soft-boiled eggs, enter 0 hours, 6 minutes and 0 seconds and press Start (or Space). Switch to a recipe in another tab: the tab title keeps counting down, 5:59, 5:58, and when it reaches 0:00 the alarm sounds and the page flashes. For a 25-minute Pomodoro work session, click the 25 min preset instead, then press R to reset it for the next round.