Reaction Time

Reaction Time measures how quickly you can respond to a visual cue. The screen stays red while you wait, and the instant it turns green you tap anywhere or press Space. You get five trials, and the delay before the green flash is randomised between 1.5 and 4.5 seconds so you cannot simply anticipate it. Your score is the average response across those trials, in milliseconds.

Two guards keep that number honest. Tapping before the green screen is a false start: the trial is discarded and repeated rather than recorded, so nobody can game the average by spamming. If you fail to react within 2000 milliseconds the trial is logged as a miss at the full 2000 ms, so hesitation costs exactly what it should. Only genuine responses ever reach the average.

Every trial reports its own result plus a plain-language rating: under 200 ms is Excellent, under 250 Great, under 300 Good, under 400 Fair, and anything slower is simply Slow. Those bands are fixed rather than scaled, so a score means the same thing every time you play. Your best average is kept locally on the device, giving you a personal benchmark to beat across sessions.

Reaction Time is a single self-contained HTML file with the whole test drawn on a canvas. There are no external images, no tracking, no cookies and no server requests, and it never asks for an account. Timing uses the browser high-resolution clock, and the test runs on phones in either orientation and on desktop with nothing to install.