Privacy policy

HanFlow is designed to teach Mandarin without requiring an account. Google synchronization and AI services are optional.

Effective date: 27 August 2026

Information stored locally

HanFlow stores learning answers, mastery estimates, preferences, downloaded model status, and optional provider configuration on your device. API keys remain in local application storage and are excluded from progress exports and Google synchronization.

Google account synchronization

If you explicitly connect Google synchronization, HanFlow requests only the drive.appdata scope. It stores per-device learning-progress snapshots, a random device identifier, a device label, and synchronization timestamps in the hidden Google Drive application-data folder.

HanFlow uses this information only to merge and restore your learning progress across your devices. It cannot access your ordinary Google Drive files. It does not sell, advertise with, or share Google user data with third parties.

HanFlow's use and transfer of information received from Google APIs adheres to the Google API Services User Data Policy, including its Limited Use requirements.

Optional AI providers

If you enable cloud AI, prompts needed for the selected learning feature are sent directly to the provider you configure. A handwriting image is also sent when you request cloud handwriting checking. If cloud AI is disabled or no provider key is saved, handwriting comparison stays in the browser. Google Drive synchronization does not send your progress to an AI provider. Offline learning and included adaptive activities remain available when cloud AI is disabled.

AI content reports

If you choose to report an AI-generated story, HanFlow sends the reported story, AI engine label, selected reason, optional note, platform type, timestamp, and random report identifiers to HanFlow's Cloudflare-hosted report store. Reports do not include your Google identity, learning progress, recordings, drawings, or API keys. Reports are retained for up to 180 days so safety problems can be reviewed and prevented.

Microphone and pronunciation clips

Microphone access is requested only when you start pronunciation or spoken-conversation practice. Audio is processed by the speech-recognition service selected on your device or in your browser. On Android, HanFlow temporarily caches only the latest pronunciation clip so you can replay it after an error. The clip is replaced by the next attempt, deleted during normal app shutdown, excluded from backups and synchronization, and never sent to a HanFlow server.

Retention and control

Local data remains until you reset HanFlow or remove the app's storage. Synchronized snapshots remain in Google Drive application data until you remove HanFlow's stored application data or delete your Google account. Disconnecting one device stops future synchronization on that device but does not erase progress from other devices.

Security

Google access tokens are short-lived and kept only in memory. HanFlow does not store Google passwords or OAuth refresh tokens. Data is transferred over HTTPS.

Age assurance

HanFlow may request an age range from Google Play to provide age-appropriate advertising and features. If an age range is unavailable, HanFlow can ask for a date of birth locally, immediately convert it to an age band, and discard the entered date. Only the resulting age band is stored on the device. Age information is used only for age-appropriate access, privacy, and advertising treatment.

Advertising

After the free question allowances, HanFlow may use Google AdSense on the website and Google AdMob in the Android app. The advertising services may process IP addresses, which can estimate general location, product interactions, diagnostic information, consent choices, and device or account identifiers for advertising, analytics, measurement, and fraud prevention. Advertising never receives HanFlow learning answers or Google Drive content. Advertising requests are encrypted in transit.

Where required, Google's consent platform presents privacy choices before advertising is requested. Those choices can be reopened from HanFlow settings.

HanFlow has no in-app purchases or subscriptions, so it collects no payment or purchase-history information.

Contact

Questions or deletion requests: [email protected].