Privacy
Your training data stays in this browser. No account, no server, no tracking. Here is exactly what that means.
No account, no sign-up
There is no registration, no email address and no password. The app does not know who you are.
Everything stays in this browser
Your profile, difficulty levels, sessions, results and achievements are written to IndexedDB on this device. They are not uploaded anywhere.
No server, no analytics, no tracking
This version has no backend. It makes no network calls for your data, loads no third-party fonts or scripts at runtime, and runs no analytics or advertising code.
Clearing your browser storage erases everything
Because the data lives only here, clearing site data, using a private window, or switching browser or device means starting from scratch. Export first if you want to keep your history.
Export and import are yours to control
Settings can write a dated JSON file containing all of your data. You choose where it goes. Importing it on another device restores your history.
Nothing is sold or shared
There is no data to sell, because none of it reaches us in the first place.
If storage is unavailable
Some browsers block IndexedDB in private windows or with strict settings. The app still runs, holding your session in memory, and shows a warning that nothing will be saved. It never fails silently.
Claims we do not make
This app is not a medical device. It does not diagnose, treat or prevent any condition, and it does not measure intelligence.
More detail on what each exercise measures is on the science page.