Privacy Policy

Last updated: September 6, 2026

Thank you for using Sudoku Fun ("the app"). The app has no ads and no third-party advertising or analytics SDKs. It talks to our own servers to power the Daily Challenge, leaderboards, sharing, online play and similar features, and it sends anonymous usage statistics to an analytics service we host ourselves so we can improve the app. This policy explains what data we process, why, and what you control.

1. Information we do not collect

No name, email address, phone number or other personal identity information
No advertising identifiers, no ad targeting, no cross-app tracking
No third-party analytics, advertising or social SDKs
No location data

2. Data stored only on your device

The following data is saved locally on your device and never uploaded:

Games and progress: current board state, draft annotations, game history
Statistics: completions, best times, streaks
Preferences: theme, display and assistance settings
Imported puzzles: puzzles you scanned or pasted, and their groups

3. Data processed for online features

When you use the following features, the app communicates with our servers. None of this traffic contains your name, email or other personal identity information. Players are told apart by an anonymous identifier generated at random when the app is installed.

Daily Challenge: fetching the day's puzzles from the server
Leaderboards: uploading your results (time, mistakes, hints, score), the anonymous identifier, and the nickname you chose. The nickname is entirely up to you — please don't use your real name or other sensitive information
Nickname review: a nickname you request is sent to the server and shown to other players only after we approve it by hand. The request (the nickname, when it was submitted, and the outcome) is kept on the server
Puzzle sharing: when you share a puzzle, the puzzle, your current progress and your nickname are stored on the server to generate the share link and code, and expire automatically after 90 days. Visitors to the share page can enter a nickname and submit their time; those entries are stored and expire together with the share
Online play and Coach mode: when you open or join a room, your nickname, board progress and draft marks are relayed through the server to the other players in that room in real time. A room closes once everyone leaves, and its contents are discarded — nothing is kept long-term
Friend invites: the invite code, the anonymous identifiers of both players, the time the code was claimed, and a device marker plus a network-address digest used to stop repeat claims (both are one-way digests that cannot be reversed) are stored on the server, solely to grant the reward and detect repeat claims
Membership and redeem codes: your membership level, type and expiry, and any redeem codes you use, are stored on the server against your anonymous identifier
Update check (Android): querying the latest version number

The anonymous identifier is not linked to your real identity and becomes invalid when you delete the app. We use this data only for the feature it belongs to, and we never share it with third parties. As with any online service, our servers receive the network address a request comes from; we do not use it to identify you.

4. Usage statistics

To learn which features are used and where things go wrong, the app sends anonymous usage statistics to an analytics service we host ourselves (Matomo, running on our own server — the data never passes through a third party).

What is recorded: which screens are opened, which features are used (such as starting a game, finishing, hints, importing), the mode and difficulty of games, the kinds of errors that occur, plus app version, OS version, device model and language
How devices are told apart: a statistics identifier generated at random when the app is installed, used only to group events from the same device. It is not an advertising identifier, contains no name or account, and is not used for cross-app tracking
Web pages: our share, Daily Challenge and room-invite pages also record page views and button taps (such as "Open app" or "Copy code"), using a random visitor identifier kept in your browser's local storage
These statistics are used only to improve the app — never for advertising, and never shared with third parties

5. In-app purchases

In-app purchases on iOS are handled by the Apple App Store under Apple's privacy policy. We receive only the transaction receipt needed to confirm your purchase status, and never see any of your payment information. On Android, membership is activated with redeem codes; see section 3 for what is stored.

6. Children's privacy

The app is suitable for all ages and does not knowingly collect any personal information from children under 13.

7. Your control

Skip the Daily Challenge, leaderboards, sharing, online play and friend invites, and games, the library and importing all work fully offline
You can request a new nickname in the app; it takes effect once approved
Usage statistics contain nothing that can identify you; there is currently no separate switch to turn them off
Deleting the app removes all local data and invalidates the anonymous identifier

8. Changes to this policy

Changes will be published on this page with an updated "Last updated" date.

9. Contact us

Questions about this policy? Reach us via the Support page.