Callback collects no personal data.
Callback has no accounts, no sign-in, no advertising, no crash reporting, and no third-party SDKs.
Anonymous usage analytics. The app sends which screen you opened (for example "learn" or "mock") to our self-hosted Umami instance at analytics.nextgensoft.co, together with the app version and your device model / OS version. Umami is cookieless and stores no persistent identifier: your IP address is used only to derive an approximate (country/city) location and a short-lived session hash, and is not stored. This data is never shared with third parties and is used only to see which parts of the app are used.
All lessons and questions ship inside the app; every feature works with the device in airplane mode. The only network request Callback makes is the anonymous analytics request described above.
Your study progress — answers, mastery scores, streaks, saved topics, and session history — is stored only on your device. It is never transmitted anywhere. You can export it as a JSON file from the Profile tab, and you can erase it at any time via Profile → Reset all data, or by deleting the app.
Callback is rated 4+ and contains no objectionable content, no user-generated content, and no communication features.
If this policy ever changes, the revised version will be posted on this page.
Questions: babin@axveer.com