Privacy Policy

Sudoku · Effective 2 May 2026

This is the privacy policy for the Sudoku app and its backend at sudoku.appfoundry.cc. The app is designed for small private friend groups to share a daily Sudoku puzzle and leaderboard. We collect only what's needed to make that work, and we don't sell or share your data with anyone.

What we collect

• Email address — used only to send a one-time verification code when you sign in. Stored on our servers so we can recognise you on future sign-ins.
• Display name — the name shown to other members of groups you join. You choose this when you sign in.
• Group memberships — which groups you've joined and when.
• Scores — for each daily puzzle you complete: the puzzle, your time, mistake count, and completion timestamp. These are shown to other members of any groups you've joined.

The app itself stores additional data locally on your device — your in-progress puzzles, settings, and game history. That data stays on your device and is never sent to our servers.

What we don't collect

• No advertising identifiers (IDFA / Android Advertising ID).
• No location data.
• No contacts, photos, or files outside the app.
• No third-party analytics.
• No advertising of any kind.

How we use your data

Your data is used solely to operate the app:

• Verifying you're you when you sign in.
• Showing your name and scores to other members of your groups.
• Generating the daily puzzle and leaderboard you see.

We don't use your data for marketing, profiling, or any purpose outside the app.

Who we share data with

We use two service providers to deliver the app:

• Cloudflare — hosts the backend and the database. Cloudflare may see metadata about requests (IP, user-agent) for security and abuse prevention. See Cloudflare's privacy policy.
• Resend — delivers the verification email when you sign in. Resend processes your email address only to send that message. See Resend's privacy policy.

We don't share data with anyone else, and we don't sell your data.

Data retention

• Your account, display name, and groups are kept until you ask us to delete them.
• Your scores are kept as part of the leaderboard history.
• One-time verification codes expire automatically and are deleted soon after.

Your rights and choices

• You can sign out from the app at any time.
• You can leave any group from the Settings sheet.
• You can request that we delete your account and all associated data by emailing the address below.

Children

The app isn't directed at children under 13. If you're a parent and believe your child has signed up, contact us and we'll delete the account.

Changes to this policy

If this policy materially changes we'll update the effective date at the top. Continued use of the app after a change means you accept the revised policy.

Contact

Questions, deletion requests, or anything privacy-related: sudoku@appfoundry.cc.