Play a few rounds a day, keep your brain moving

It depends which skill. Spatial training has the strongest evidence: the Uttal et al. meta-analysis of 206 studies (Psychological Bulletin, 2013) found an average effect of g = 0.47 with transfer to untrained spatial tasks. Memory and attention training is the opposite -- trained scores rise, but transfer to everyday performance has stayed weak, per the Simons et al. review (2016). This site reports that difference instead of one blanket answer.

Accurate for comparing you against yourself, much less so for comparing you against other people. Browsers and hardware add tens of milliseconds of their own -- Bridges et al. (PeerJ, 2020) measured 15-67 ms of visual lag and 8-48 ms of input lag -- so cross-device leaderboards mean little. Keep the device and input method fixed and the change between two of your own sessions is trustworthy.

Twelve tests across five categories: reaction (reaction time, aim trainer, choice reaction), memory (number memory, visual memory, sequence memory), thinking (sudoku, code breaker), attention (Schulte table, Stroop test) and spatial (mental rotation, sliding puzzle). All free, no account, nothing to install, and a round takes anywhere from one to a few minutes.

No. A formal intelligence assessment is a standardised battery with published norms and an administration protocol, given and interpreted by a trained professional. This site measures your performance on one specific task -- how many digits you held, how many milliseconds you took -- and converts it into no intelligence score and no diagnosis.

No reliable research supports a specific daily dose, so this site does not prescribe one. Fixing the conditions matters more than fixing the duration: same device, same input method, roughly the same time of day, so that two sessions are comparable. Each test runs under a minute, and three to five rounds is enough for a stable number.

They measure three unrelated things. The Schulte table measures how fast you locate targets in a cluttered field, scored in seconds. Sudoku measures deduction from stated conditions to a single answer, scored in time and backtracks. A reaction test measures the gap between seeing and acting, scored in milliseconds. The three scores are not comparable and should not be averaged.

Yes -- none of them has an age requirement beyond recognising numbers and colours. Just do not read the results against adult reference ranges: children's abilities shift with age anyway, and reaction time in older adults is generally slower than the early-twenties peak. In both cases the useful signal is the person's own change over a few weeks.

No. Scores are written to your browser on this device only. Nothing is uploaded, no account is needed and no personal details are asked for. The trade-off is that clearing your browser data or switching devices loses the history -- that is the cost of not handing over any personal information.