Chronometer — Stopwatch & Countdown Timer
Free online stopwatch and countdown timer with lap tracking, millisecond precision, preset durations, and visual countdown progress bar.
AI developer workflow fit
Use Chronometer — Stopwatch & Countdown Timer while building with AI coding assistants, agents, and LLM workflows: validate generated output, transform payloads, debug integrations, and prepare reliable inputs without leaving your browser.
What Is the Chronometer Tool?
The Chronometer tool combines a precision stopwatch and a countdown timer in a single interface. The stopwatch measures elapsed time with millisecond accuracy and supports lap splits, while the countdown timer lets you set a target duration with quick presets and provides a visual progress bar plus an alert when time expires. Both modes use requestAnimationFrame for smooth, battery-friendly display updates.
How to Use the Chronometer
- Switch between Stopwatch and Countdown using the tabs at the top.
- In Stopwatch mode, click Start to begin timing, Lap to record a split, Pause to halt, and Reset to clear.
- In Countdown mode, enter hours, minutes, and seconds or pick a quick preset (1 min, 5 min, etc.).
- Click Start to begin the countdown. The progress bar fills as time elapses.
- When the countdown reaches zero the display flashes red to alert you.
- Use Pause to temporarily stop and Resume to continue from where you left off.
Common Use Cases
- Performance Benchmarking — Measure how long a manual process or deployment step takes so you can compare optimizations over time.
- Pomodoro & Focus Sessions — Set a 25-minute countdown for focused work intervals followed by short breaks.
- Meeting & Presentation Timing — Use the countdown timer to keep meetings on schedule or time individual presentation segments with laps.
- Debugging & Profiling — Time specific user workflows in a browser or application to identify slow interactions before diving into profiling tools.