Yes, completely free with no signup or ads.

Does my data leave my device?

No. Your reaction history and best time are stored only in your browser's localStorage.

Does it work on mobile?

Yes. Tap the area on iOS Safari or Android Chrome — touch input is fully supported.

Mide tu reacción — haz clic justo cuando la pantalla se vuelve verde.

Last

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Mejor

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Avg (5)

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Last 5 attempts

Click the dark area to start. It will turn red and show a "Wait…" message — don't click yet.
After a random delay (1–4 seconds) the area turns green and shows "Go!" — click or tap it immediately.
Your reaction time is shown in milliseconds. Clicking before it turns green counts as a false start and resets the attempt.

Is it free?: Yes, completely free with no signup or ads.
Does my data leave my device?: No. Your reaction history and best time are stored only in your browser's localStorage.
Does it work on mobile?: Yes. Tap the area on iOS Safari or Android Chrome — touch input is fully supported.

Last updated: 2026-05-20 By jarvisbox