Privacy Policy

Effective 4 November 2026

Box Brain Sudoku is published by Superserve ("we"). This policy explains what the app and this website do with data. The short version: there is no account, we run no servers that hold your data, and your progress stays on your device and in your own iCloud.

What the app stores

Puzzle progress, settings, statistics and purchase status are stored on your device. Nothing you enter in the app is sent to us.

Sync and Game Center

To keep your progress across your devices and after reinstalling, the app keeps a copy of it in iCloud key-value storage on your Apple Account. If you sign in to Game Center, it also keeps a copy in Game Center saved games and submits your scores to Game Center leaderboards and achievements. These copies are held by Apple under Apple's privacy policy; we can't read them. You can also export a backup file yourself in Settings.

Advertising (free version only)

The free version shows ads through Google AdMob. AdMob may collect device identifiers, approximate location derived from your IP address, and ad interaction data to serve and measure ads, as described in Google's privacy policy and the AdMob partner list.

In the European Economic Area, the United Kingdom and Switzerland, the app asks for your consent before showing personalised ads, and you can change your choice at any time in Settings › Manage ad consent. On iOS the app asks for tracking permission; if you decline, ads are shown without cross-app tracking.

Buying Box Brain Pro removes all advertising, and the AdMob SDK is no longer started.

Purchases

In-app purchases are processed by Apple through the App Store. We receive no payment details. Purchase status is stored on your device and can be restored from your Apple Account.

Analytics

The app sends anonymous usage events (for example "puzzle completed, variant Killer, difficulty Hard") to TelemetryDeck, a privacy-first analytics service that does not store personal data or IP addresses. Events contain no puzzle content and no identifiers that can be linked to you.

Crash reports

If the app crashes, a report with the device model, OS version, app version and the technical stack trace is sent to Sentry to help us fix the problem. Reports contain no personal data, no IP address and no screenshots.

Challenge links

When you challenge a friend, the link holds the puzzle, your time and, if you add one, the name you typed. You choose where to send it. If your friend opens it on this website, the page reads the puzzle from the link in their browser; nothing is stored.

This website

This website uses no cookies, no analytics and no ads. It is hosted by Cloudflare, which processes visitors' IP addresses to deliver the pages and protect against abuse, as described in Cloudflare's privacy policy.

Children

The app is intended for a general audience and does not knowingly collect personal information from children.

Changes and contact

We will update this page when the app's data practices change, and change the date at the top. Questions: [email protected].