iStopwatch is a small set of free, browser-based time tools: a stopwatch, countdown timer, interval/Tabata timer, world clock and date calculator. Everything runs directly in your browser using your device's own clock — there's nothing to install and no account to create.
The goal is simple: fast, accurate, distraction-free timers that work the same way every time, on desktop or mobile.
Stopwatch — start, stop and record lap times with millisecond accuracy. Countdown Timer — set a custom or preset duration and get an alert when it hits zero. Tabata / Interval Timer — build a fully customizable work/rest interval workout. World Clock — track live times in multiple cities and convert between time zones. Date Calculator — find the days between two dates or add/subtract time from a date.
No installs, no accounts, and no clutter. Every tool loads instantly, works offline once loaded, and is built to be used again and again without getting in your way.
iStopwatch is free to use and is supported by advertising. Ads are served through Google AdSense; see our Privacy Policy for details on how ad partners use cookies and data, and our Terms of Service for the rules of using the Site.
Have feedback, found a bug, or have an idea for a new tool? We'd love to hear from you.