Privacy Policy
Last updated: 7 October 2026
The short version. Sudoku Workshop, on Android and iPhone or iPad, has no account, no advertising and no analytics of its own. Your puzzles, progress and settings are stored on your device and are never sent to the developer. The app relies on Google’s handwriting recognition on both platforms, and on the platform’s own store for purchases - Google Play on Android, the App Store on iPhone and iPad. Each is described below.
What is stored on your device
The app keeps the following in its private storage, which other apps cannot read:
- Your puzzles: the information needed to recreate each puzzle (a seed, its size, difficulty and variant), the digits and pencil marks you have entered, time played, whether it is finished or starred, and the date for daily puzzles.
- Your settings: theme, input method, highlighting and timer preferences, the daily puzzle difficulty, and whether the daily reminder is on and at what time.
- Your training and badges: which practice positions you have solved, which badges you have already been told about, and whether you have shared a puzzle. Stats and badges themselves are worked out from your puzzles each time and are not stored separately.
None of this is transmitted by the app. Your phone or tablet’s own backup may include it: on Android, a backup to your Google account, governed by Google’s Privacy Policy; on iPhone and iPad, an iCloud or computer backup, governed by Apple’s Privacy Policy. Deleting the app deletes this data from your device.
Handwriting recognition
Handwriting input uses Google’s ML Kit Digital Ink Recognition. The first time you use it, the app downloads a recognition model from Google, roughly 20 MB. After that, recognition runs entirely on your device and works offline. The strokes you draw are used only to recognize the digit, are not stored, and are not sent anywhere.
According to Google, ML Kit may contact Google’s servers to receive model updates and fixes, and may send Google limited information about the device, the app and how the recognition feature performs. This does not include your handwriting. Google describes this in its ML Kit data disclosures for Android and iOS. On iPhone and iPad, ML Kit’s own privacy declaration lists the kinds of data it may send: a device identifier, performance and other diagnostic data, how the feature is used, and data about the recognition itself - none of it linked to you, and none of it used to track you. If you never switch to handwriting input, the model is never downloaded.
Purchases
The Unlimited subscription and the Lifetime unlock are sold through the store you installed the app from: Google Play Billing on Android, and the App Store on iPhone and iPad. The store handles the payment, and the app never sees or stores your name, email address, payment details or billing address. The app receives only a confirmation from the store of which products your account owns, which it uses to unlock features. See Google Play’s Terms of Service or the Apple Media Services Terms for how each handles payment information. You can manage or cancel a subscription in the Google Play Store, or in your Apple Account’s Subscriptions settings.
Notifications
The optional daily reminder is scheduled and shown by the app on your device. No server is involved. The app asks for notification permission only when you turn the reminder on. On Android it uses the RECEIVE_BOOT_COMPLETED permission only to reschedule the reminder after your phone restarts; on iPhone and iPad the reminders are scheduled with the system ahead of time.
Network access
The app has no server of its own and makes no network requests of its own. It needs internet access only for downloading the handwriting model and for communicating with the store about purchases. Puzzles, including the daily puzzle, are generated on your device. A shared puzzle link carries only the puzzle itself; opening one involves no server beyond your browser loading this website.
Third-party code
The app includes Google ML Kit on both platforms and Google Play Billing on Android. It contains no advertising, analytics or crash-reporting libraries of its own. If the app crashes, your device may offer to send a report to Google or Apple. That is a feature of the device that you control in its settings, not something Sudoku Workshop requests.
Children
Sudoku Workshop is a general-audience puzzle game. The developer does not collect personal information from anyone, including children.
Changes
If this policy changes, the new version will be published on this page with a new “last updated” date.
Contact
Questions about this policy can be sent to the developer contact email listed on the app’s Google Play store page or its App Store page.