Privacy policy

The short version

• Core gameplay and every save start on your device and work offline.
• Firebase Analytics receives a small fixed set of product events, never puzzle entries, notes, names, or advertising identifiers.
• Friends, ranked play, Apple account backup, updates, and tips use the network only when needed.
• You can delete local history, backed-up progress, online player data, and your account from Settings.

Friends and online play

When you use friends or online play, Open Sudoku creates a random guest identity. The Vercel-hosted API stores generated player names, friend relationships, private races, ranked attempts, leaderboard results, and opaque login sessions in a European Postgres database. Other players see generated names and relevant results, not email addresses or Apple account details.

Apple account progress backup

If you choose Sign in with Apple, the same European Postgres database stores your puzzle identifiers and grids, entries, pencil notes, elapsed time, mistakes, hints used, completion state, and save timestamps. This restores progress across devices. Deletion markers are retained with the account so an older offline device cannot recreate games you erased. The app does not store your Apple email address.

Product analytics

Firebase Analytics is used for aggregate product decisions. Advertising storage, advertising user data, ad personalization, automatic screen reporting, and identifier-for-vendor collection are disabled. Analytics is not used for advertising.

Connected services

Apple verifies optional account sign-in, Vercel and Neon provide the account backend, Firebase provides aggregate product analytics, and Apple StoreKit processes optional tips that unlock nothing. These providers process the technical data necessary to deliver their services.

Retention and deletion

Signed-out local history remains until you delete it or remove the app. While signed in, Delete Puzzle History Everywhere removes game snapshots from the device and backend; the backend keeps small deletion markers so an older offline device cannot recreate erased games. Delete Account removes the profile, backed-up progress, deletion markers, friends, races, rankings, reports, and login sessions after fresh Apple authorization. Legacy private iCloud records created by an earlier app version are not read or updated by the current app and remain subject to Apple’s iCloud controls. Provider records follow Apple, Google, Neon, and Vercel retention controls.

Contact

Privacy requests: persianov.petr@gmail.com.