Multiple countdown timers at once, with a real alarm sound, background-tab alerts and Pomodoro-style sequences.
This timer was built to solve the most common bug in browser countdown timers: drifting once the tab goes to the background. Instead of counting tick by tick with setInterval (which browsers throttle or freeze to save battery), each timer stores only the exact instant it should finish and recalculates the remaining time whenever the page runs again, so the result is always exact no matter how long the tab stayed out of focus. You can keep several timers running at once, each with its own name, color, alarm sound and volume, chain focus/break steps like a Pomodoro cycle, and share a single timer's setup through a link.
Paste the code into your HTML and the tool shows up on your page, without J-Kit's navigation and ads. It still runs in the browser of whoever visits your site.
<iframe
src="https://jkit.tools/embed/en-US/online-timer"
width="100%"
height="600"
style="border:0"
loading="lazy"
title="Online Timer"
></iframe>These references help contextualize formulas, standards, APIs and limitations used on this page. They do not replace professional validation when a result has legal, financial, medical or operational impact.
Yes. Instead of adding up seconds on every tick, the timer stores the exact millisecond instant the countdown should end and recomputes the remaining time from the real clock whenever the page runs again. Switching tabs, minimizing the window, or the browser throttling setInterval to save battery never throws off the final result.
Loading saved timers...
Everything runs in your browser: the timers, the alarm audio and the countdown never touch a server. The list is saved locally (localStorage) on this device only.