Privacy Policy

The short version

Number System Trainer does not require an account and does not collect your name, email address, contacts, location, advertising identifier, payment-card information, or the songs and practice content you use in the app. We do not show ads or track you across apps or websites.

Privacy-friendly app analytics

We use TelemetryDeck, provided by TelemetryDeck GmbH in Germany, to understand which lessons and features are useful and where the app needs improvement. TelemetryDeck receives an anonymized identifier created for this app installation, app interaction events, an approximate event time, app version, platform, and limited fixed labels such as the lesson or feature involved.

The installation identifier is not tied to an account or real-world identity. We do not send names, email addresses, advertising identifiers, free-form text, song content, or practice content. TelemetryDeck does not store IP addresses, use cookies, or use this information for advertising or cross-app tracking.

Learn more in TelemetryDeck's privacy policy and privacy FAQ.

Purchases and information on your device

In-app purchases are processed by Apple. Number System Trainer receives only the information needed to determine whether the app has been unlocked; we do not receive your payment-card details. Your learning progress, settings, and purchase entitlement are stored on your device or managed by Apple. Removing the app may remove locally stored progress.

Retention and your choices

Anonymous analytics are retained only as needed to evaluate and improve the app and according to TelemetryDeck's retention practices. Because the analytics are not connected to your identity or an account, we generally cannot identify or retrieve an individual person's analytics records.

Changes and questions

We may update this policy when the app or its services change. The effective date above will reflect the latest revision. For privacy questions, use the developer support contact on the app's App Store page.