Simple visual reaction time averages roughly 250–300 ms in adults, with teens and young adults often a bit quicker (around 200–250 ms) and times slowing gradually with age. On AnyTool, an average under about 215 ms is rated “Fast!” and under 180 ms “Lightning”. The theoretical floor for a genuine human reaction is around 100–120 ms, so any click faster than that is anticipation rather than a real response — the tool flags those as “Too soon!” and does not score them.

When the panel turns green, AnyTool captures the time with performance.now(), a monotonic high-resolution clock. When you click, tap, or press Space, it captures the time again and reports the difference, rounded to the nearest millisecond. The wait before green is randomized between 1.5 and 5 seconds using the Web Crypto API (crypto.getRandomValues), never Math.random, so you can’t feel the rhythm and jump early. Over a series of trials it shows your average, median, best and worst, since a single click can be lucky or unlucky.

Any browser-based reaction test measures more than your nervous system: the time for the green frame to actually appear depends on your monitor’s refresh rate, and your mouse or touchscreen plus the browser add input latency. Together that can add a few milliseconds to several tens of milliseconds (some TVs add 100 ms or more). That is why results are best treated as relative — ideal for comparing your own runs or competing on the same device — rather than a clinical figure. Warm up, run several trials, and use the average or median instead of a single click.

AnyTool Reaction Time Test runs entirely client-side. The random delays, the timing, and all statistics are computed locally and never sent to a server, logged, or tracked. The only thing kept between visits is your single best score, stored in your browser’s localStorage on this device — you can clear it anytime by clearing site data. There is no account, no sign-up and no upload, and the page works offline once cached.