Privacy Policy

Effective / updated October 31, 2026

1. Operator and scope

Next Studio (South Korea) operates Number Cross (com.osj.numbercross), a math crossword puzzle for iOS and Android. This policy covers the app and this support website. Privacy contact: dhalska2@gmail.com.

2. Game data on your device

Puzzle progress, cleared stages, hint-use counters, the current board and your settings (theme, haptics, input options) are saved on your device. Deleting the app removes them. They are not uploaded as a save file.

3. Hints, rewards and purchases (our server)

The app signs in to our server anonymously: no name, e-mail or password is asked. We store an anonymous user ID, your hint balance and a ledger of hint grants and spends (request IDs and times), rewarded-ad voucher records, and purchase records (product ID, store, environment and a one-way hash of the transaction or purchase token). Hints are granted and spent only by the server, so hints need an internet connection; normal play works offline. Payment is handled by Apple or Google Play; we never receive card details. When you buy or restore ad removal, the app sends the store purchase proof to our server, which verifies it with Apple or Google before unlocking it.

4. Advertising and privacy choices

The app shows Google AdMob interstitial ads and optional rewarded ads. We request non-personalized ads only, and where required a Google consent message (UMP) is shown; you can change the choice in Settings. The advertising SDK may process IP address, approximate location inferred from it, device and advertising identifiers (on Android, the advertising ID), ad views and clicks, diagnostics and your consent choice to serve and measure ads and prevent fraud. We do not use App Tracking Transparency and do not track you across other companies’ apps. For a rewarded ad our server stores a pseudonymous voucher token, the ad transaction ID and the time to prevent duplicate rewards. Advertising disclosures may count as sharing under local law; we do not claim that no data is collected.

5. Crash reports

Release builds send crash and error reports to Google Firebase Crashlytics (stack traces, device model, operating system, app version, a per-installation identifier). They are used only to fix defects. Debug builds do not send reports. We do not use Firebase Analytics.

6. Server location, retention and providers

Our database (Supabase) is located in Seoul, South Korea; Supabase and its subprocessors may provide operational support from other countries, including the United States. We use Apple and Google for payment and ads, Google Firebase for crash reports, and GitHub Pages for this website. Anonymous server records are kept while the app is in use. Purchase records (transaction hash, product, time; no personal data) are kept for refund handling and accounting. Device data is removed by deleting the app.

7. Your rights and deletion

You may ask to access, correct or delete the data we hold about your anonymous ID, or object to processing, by e-mail to dhalska2@gmail.com. Because the ID is anonymous we may need the app version and a description of when you used the app to find it; do not send passwords or card details. Processing relies on contract performance (running the game and verifying purchases), legitimate interests in security, fraud prevention and fixing defects, legal obligations, and consent where required (ad choices). See the Data Deletion page for the steps.

8. Children and changes

Number Cross is not directed to children under 13 and we do not knowingly collect personal information from them. If this policy changes, we update the date above and, for material changes, notify you in the app or on this site.