Last updated: June 2026
Summary
Number Trainer is designed to work with minimal data collection. Today there are no user accounts. Most progress stays on your device. Speech is generated by contacting a server (yours or the host’s) and Microsoft’s TTS service.
Stored on your device
-
Progress — levels unlocked, numbers heard, practice stats, and
preferences (languages, speech speed, practice options) in browser
localStorage. -
Audio cache — generated speech clips in
IndexedDBso repeated numbers load faster. You can clear this by clearing site data for the app. -
Mobile config — the Capacitor build may include a
config.jsonwith the API server URL (apiBase).
Sent to the app server
When you hear a number, the client requests audio from the API. Typical requests include:
- The number and practice language (and speech speed).
- Standard HTTP data such as IP address, user agent, and timestamps — as with any web request.
The server does not require a login today and does not persist a user profile from these requests. Server logs depend on how you host the app (Railway, Fly.io, your own VPS, etc.).
Text-to-speech provider
Speech is synthesized through Microsoft Edge online TTS (via
edge-tts-universal). Number text and language are sent to that service to
produce audio. That service is operated by Microsoft and subject to Microsoft’s terms and
privacy practices. This integration is unofficial and may change without notice.
Fonts
The UI loads fonts from Google Fonts. Google may receive your IP address and basic technical data when fonts are fetched. See Google’s privacy policy.
Future accounts
If sign-in and server-synced progress are added later, this policy will be updated to describe what account data is stored, how long it is kept, and how to delete it.
Children
The app does not knowingly collect personal information from children. It does not ask for a name or email in the current version.
Your choices
- Clear progress by removing site data / app storage in your browser or device settings.
- Stop using the app at any time.
Contact
Questions about privacy can be sent through the project repository or the feedback channel once it is available.