About ReactionTiming

ReactionTiming exists because measuring your reflexes should take ten seconds, not an account signup and a download. Every game here loads instantly, runs entirely in your browser, and works the same on a phone as on a desktop.

What we build

Four things: a one-click reaction time game for a quick number, a five-round test for a number you can trust, an endless speed streak for training sustained attention, and a 1v1 battle for settling arguments. The training guide covers what actually improves reaction speed and what does not.

How we measure

Timing uses the browser's high-resolution clock, started at the frame where the signal appears and stopped at your input event. Delays before each signal are randomized so anticipation cannot be substituted for reaction, and early inputs are voided rather than scored. Absolute times include display and input latency, which typically adds 20 to 40 milliseconds compared with laboratory equipment — so treat the score as precise for tracking yourself over time and approximate for comparing against published research.

Your data

Scores live in your browser's local storage and never reach a server. There is no account, no profile, and nothing to delete on our side. See the privacy policy for the full detail, or get in touch with feedback and bug reports.