Privacy Policy for Matubi

1. Controller

The controller responsible for processing personal data in connection with Matubi is:
Nguyen Anh Tuan · Topivo
Georgi-Dimitroff-Str. 3
06132 Halle (Saale)
Germany.

Contact for Matubi, privacy and deletion requests: [email protected].
General operator contact listed in the Topivo Legal Notice: [email protected].

2. About Matubi

Matubi is a mathematics learning app for children in grades 1–4. Learning paths, exercises, error training and small learning games support practice of basic mathematics. This policy covers the Matubi Android app and its account, learning, purchase and advertising features. Visits to the Topivo website are also subject to the website privacy policy.

3. Data we process

Depending on the features you use, Matubi processes:

• Account and login: email address, internal account ID, authentication and session tokens, and information for email/password login or Google Sign-In.
• Matubi ID: a separate account identifier in the format MTB-…, used for account identification and support. It is not an anonymous identifier.
• Learning profile: chosen profile name, avatar selected from the app, grade, language and app settings.
• Learning and game data: completed topics, exercise and game histories, answers, correct and incorrect results, practice times, daily goals, XP, Coins, Stars, Level, Streaks, unlocked content and achievements.
• Error training: stored tasks, incorrect answers, repetitions and completion status.
• Monthly challenge: grade, month, relevant exercise results, stars, rank, display information and, where applicable, rewards or result history.
• Premium and purchases: purchase and entitlement status, product identifier, purchase time, expiry date and purchase restoration information; where applicable, entitlements granted through gift codes.
• Technical data: IP addresses during network connections, session, request and synchronization information, timestamps, and app and device information needed for SDK operation, troubleshooting and abuse prevention. Provider-specific details are explained below.

4. Supabase

Matubi uses Supabase for authentication and server-side database and backend functions. These include login, session renewal, password recovery, storage and synchronization of learning profiles and progress, and server-side verification of learning rewards and challenge results. Stored information is linked to the signed-in account.

Avatar selection uses predefined app avatars. It does not provide uploads of personal photos; this policy therefore does not claim that user photo uploads are processed through Supabase Storage. This policy does not guarantee that the server region is exclusively in Germany or Europe. Further information: Supabase Privacy Policy.

5. Google Sign-In

Google Sign-In uses an OAuth login flow through the system browser and Supabase. Google confirms authentication and Supabase provides a Matubi account session. Matubi uses the associated account ID and email address for login and account identification. Depending on information released by Google, basic profile information may be included in returned account metadata.

Your Google password is entered during Google’s login flow and is not stored as a Google password in Matubi. This login does not authorize Matubi to access your Google mailbox, contacts or Drive files. Google’s processing during authentication is explained in the Google Privacy Policy.

6. Google Play Billing and RevenueCat

Paid Android purchases and subscriptions are processed through Google Play. Matubi uses RevenueCat to retrieve purchase status and Premium entitlements, restore purchases and manage access to features. The internal account ID is passed to RevenueCat as the app user identifier. Processing includes purchase history, product and transaction information, entitlements and related timestamps, and technical information needed to operate the service.

Matubi does not directly receive or store full payment-card or bank-account details. Payments are handled by Google Play and its payment providers. Account deletion and subscription cancellation are separate: a Google Play subscription must be managed or cancelled through Google Play. Further information: RevenueCat Privacy Policy and Google Privacy Policy.

7. Google AdMob

The free version may display banner ads and optional rewarded ads through Google AdMob. The app suppresses advertising when a Premium or Lifetime entitlement is active. This does not guarantee that no technical SDK connection occurs when the app starts.

The Android implementation requests non-personalized ads. Ad requests are tagged for child-directed treatment and users below the age of consent, with the maximum ad content rating set to “G”. The Android configuration also removes permission for the Android advertising ID and permissions for precise and approximate device location. These technical settings are not a privacy certification.

Non-personalized advertising still involves data processing. During SDK connections and ad delivery, Google may process IP addresses, approximate location inferred from them, ad interactions, and technical diagnostic and device information. The scope and identifiers depend on SDK version, device settings and child-protection configuration. This policy does not claim that the app includes a separate consent dialog. Further information: Google Privacy Policy and Google Mobile Ads SDK data disclosure.

8. Children and privacy

Matubi is intended for children and families. Accounts are managed in the Parent Area. A child’s learning profile uses a grade and chosen display name; learning features do not require a publicly visible full name. Please use a nickname and do not include an address, school or other sensitive information in profile names.

The Parent Area uses a calculation as an access barrier. It is not reliable verification of age, identity or parental authority, and does not replace any consent required by law. Parents and legal guardians may contact [email protected] with questions or to exercise rights regarding a child’s data. Matubi does not claim a special privacy or child-protection certification.

9. Learning and usage data

Learning information is stored so children can resume their progress, receive suitable exercises and error training, and synchronize progress between signed-in devices. Results and practice times support progress displays, daily goals and weekly summaries. XP, Coins, Level, Streaks and achievements support reward and learning features.

Server-verified learning sessions process task configurations, answers, results, timestamps and time-zone information to calculate rewards and challenge scores consistently and limit duplicate credits or manipulation. These learning functions are distinct from technical data processing by advertising and purchase providers.

10. Monthly challenge and Top 10

The monthly challenge evaluates eligible, server-confirmed exercise sessions by month and grade. The leaderboard is visible within the app to signed-in users. It shows rank, stars and a limited display name. Other participants’ names are shortened to the first letter followed by “•••”; your own entry may show your nickname. Email addresses, Supabase user IDs and Matubi IDs are not displayed as public leaderboard fields. Names resembling email addresses or account identifiers are filtered from the name display.

Account-linked challenge data is stored internally for calculations, account association and result history. Historical results are separate from a simple learning-profile reset. Deletion requests also consider these separately stored records; signing out or resetting a profile does not guarantee automatic deletion of all challenge history.

11. Offline use

The app stores session information, settings, learning progress, results, error-training data and certain status displays locally on the device. This caching supports features without a continuous internet connection and later synchronization or resubmission of pending learning records. Login, purchases, current leaderboards and certain server-verified rewards require a connection.

Signing out or uninstalling does not automatically delete the server-side account. Local data may also be affected by device backups and restoration. To request full account deletion, use the contact method in section 13.

12. Retention

Account-linked data is stored to operate and manage the account and provide its learning features. Retention depends on the processing purpose, any deletion request and applicable legal retention or evidentiary obligations. No single fixed retention period is promised for all data categories.

Learning progress, purchase records, abuse-prevention data, challenge history and technical backups may have different retention requirements. When a deletion request is received, we review the affected records and explain exceptions required by law or necessary for legal claims. Data without a continuing processing purpose must be deleted or effectively anonymized. Google and other providers’ independent retention rules remain applicable to their own processing.

13. Deletion and your rights

Request account and data deletion: email [email protected] with the subject “Matubi account deletion”. Include the account’s email address or Matubi ID and specify whether you want the entire account or particular data deleted. Parents and legal guardians can submit a request for their child. Do not send passwords or payment-card details. Where necessary, we verify account identification and authority before processing the request.

A profile reset, signing out or uninstalling is not full account deletion. Requests cover review and deletion of associated account, learning, profile and challenge data, and applicable provider data. Legally required records may be exempt from deletion; any restrictions will be explained. Cancel an active Google Play subscription separately in Google Play. See the Matubi account deletion page for step-by-step instructions. Deletion requests do not require a Premium purchase.

Subject to the GDPR, you have rights of access, rectification, erasure, restriction and data portability, and the right to object to processing based on legitimate interests. Consent can be withdrawn for future processing. You may lodge a complaint with a data protection supervisory authority. Contact [email protected] to exercise your rights.

14. Recipients and service providers

The described functions use Supabase for authentication, database and backend services; Google for Google Sign-In and Google Play, and Google AdMob for advertising; and RevenueCat for purchases and Premium entitlements. Each provider receives data needed for its function. Authorities or other recipients are involved only where required by a legal obligation or lawful enforcement of rights.

These international providers may process or access data outside the European Economic Area. This policy does not guarantee exclusively European storage or any particular unverified certification or contractual arrangement. Transfers to third countries must meet the requirements of Articles 44 et seq. GDPR. You may request information about recipients and transfer grounds relevant to your data using the contact details above.

15. Legal bases

Account, learning and purchase management relies on Article 6(1)(b) GDPR where necessary to provide agreed features. Legal obligations rely on Article 6(1)(c). Necessary security and abuse prevention may rely on Article 6(1)(f), with particular consideration of children’s interests. Processing requiring consent may take place only on the basis of valid consent under Article 6(1)(a).

AdMob’s child-directed and non-personalized advertising configuration is not itself consent and does not replace a required legal basis. Access to information stored on devices is also subject to applicable rules, particularly section 25 of Germany’s TDDDG; technically necessary access must be distinguished from access requiring consent. This policy does not claim blanket consent through use of the app.

16. Changes to this policy

We update this policy when relevant app features, data processing or legal requirements change. The current version is available at topivo.net/apps/matubi/datenschutz/. We provide notice of material changes where legally required.

17. Contact

For questions about your data, child profiles or deletion requests, contact [email protected].
The controller and postal address are listed in section 1. The general operator contact is [email protected].