Short version: the trainer works with no account at all, and if you use it that way nothing about you leaves your browser. Signing in stores your email address and your progress, and nothing else. There is no tracking, no analytics and no advertising anywhere on this site.
Every mode works signed out. Your progress — which chart cells you have mastered, your accuracy heatmap, your counting streaks, your settings — is written to your own browser’s local storage and is never sent anywhere. Clearing your browser data deletes it, and nobody, including us, has a copy to restore.
Signing in exists for one reason: so that progress survives clearing your browser and appears on your other devices. It unlocks nothing. Here is the complete list of what is stored on the server when you do:
| Why it exists | |
|---|---|
| Your email address | So the app can show you which account you are signed in as. It is not used for anything else, and there is no mailing list to be added to. |
| A Google account identifier | The opaque id Google issues for you. It is what recognises you as a returning user, and it means a changed email address does not lose your progress. |
| Your progress | The same data the browser-only version keeps locally: mastered cells, accuracy, streaks, bankroll and settings. |
| A session token | Proof that this browser is signed in. Only a one-way hash of it is stored, so the table is useless to anyone who reads it. |
No password is ever created or stored, because Google does the identifying. There is no credential here to be leaked. The app asks Google for two things only — a subject id and an email address — and declines the name, profile picture and everything else it offers.
Settings → Account → Delete account. It removes your email address, your Google identifier, your sessions and your stored progress from the server immediately and permanently. There is no soft delete and no recovery window, and you do not have to email anyone to ask.
Signing out, by contrast, leaves everything where it is — including the copy in your browser, so signing out does not cost you your progress.
The site and its database run on Cloudflare. Sign-in is handled by Google, so your interaction with Google’s sign-in screen is covered by Google’s own privacy policy rather than this one.
If what is stored ever changes, this page changes with it, and the change is visible in the site’s public commit history rather than announced by a banner nobody reads.
Back to the trainer No account needed, and none asked for.
No. Every drill and every mode works signed out, with your progress saved in your own browser. An account only adds a copy on the server so your progress survives clearing your browser and appears on other devices.
No password is ever created or stored. Signing in is handled by Google, so the only thing proving who you are lives with Google.
No. There is no analytics of any kind and no advertising. The only cookie is the one that keeps you signed in, and it only exists if you choose to sign in.
Settings, then Account, then Delete account. It removes your email address, your Google identifier and your stored progress from the server immediately and permanently.