Stopwatch
Precise timing tool with lap tracking, multiple timers, and session management for all your timing needs
About the Stopwatch
This is a stopwatch that runs entirely in your browser with no round trip to a server, so the displayed time reflects your own clock and keeps running smoothly even on an unreliable connection.
It supports several timers at once, lap recording within a run, and exporting a session as a PDF report when you need a record of the intervals.
How to use it
- 1Start the stopwatch with the start control, or set up more than one timer when you need to time independent activities.
- 2Record a lap at each checkpoint; every split is stored with its running total so you can see individual segment times.
- 3Pause and resume as needed without losing accumulated time.
- 4Export the session — with laps and totals — as a PDF when you are finished.
When you would use it
- Timing intervals with lap splits — training sets, a run-through of a presentation, a cooking step.
- Running several named timers at once for a workshop or a classroom rotation.
- Keeping a record of each split rather than only the final total, then exporting it.
How it works, and what it does not do
This tool runs entirely in your browser. There is no server involved and nothing is transmitted — the page is the whole program, so it also keeps working offline once loaded. Elapsed time is computed from the system clock rather than by adding up timer ticks, which means it does not drift and it does not pause while the tab is in the background.
The consequence of being local is that the session belongs to the page. Reloading, navigating away or closing the tab ends it, and there is no account behind it to restore from. That is the trade for having nothing uploaded, and it is why the export exists.
Frequently asked questions
Will the timer keep running if I switch tabs?
Yes. The elapsed time is derived from timestamps rather than from a counter incremented once per frame, so the value stays correct even if the browser throttles the page while it is in the background.
What is the precision of the displayed time?
Hundredths of a second are displayed. Actual accuracy is bounded by the system clock and by how often the browser repaints, so treat sub-second differences as indicative rather than laboratory-grade.
Is my session data saved anywhere?
No. Everything stays in the page and is lost when you reload or close it, which is why the PDF export exists — it is the way to keep a permanent record.
Does the stopwatch keep running in a background tab?
Yes. Elapsed time is derived from the system clock, so browsers throttling a background tab does not affect the result — only the on-screen refresh rate. Switch back and the display catches up to the correct time.
Can I time more than one thing at once?
Yes. You can create several named timers and control them independently, which is what makes it usable for rotations where one segment overlaps another, or for timing two speakers in the same session.