World of Cultures app icon World of Cultures
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Privacy Policy

Last updated: October 18, 2026

1. Introduction and Data Controller

This policy explains how "World of Cultures" (the "app") collects, uses, stores, shares and protects your personal information, and what rights you have. Please read it before using the app.

Data controller: Xue Wentao (individual developer). Operating entity: QianYujie Culture Technology (Shenzhen) Co., Ltd. Contact: qianyujie_app@163.com.

This policy applies to all versions of the app (including the mainland China version and the overseas version). The cloud services used differ by version; see Sections 5 and 7.

2. Information We Collect

  1. Account information: when you sign in with email (including passwordless email links) we collect your email address; with Google Sign-In we receive the Google account identifier, email address, display name and profile picture you authorize; with Sign in with Apple we receive the Apple account identifier and the name and email address you choose to share (you may hide your real email, in which case we only see Apple's private relay address); with WeChat sign-in (mainland China version) we receive, through the WeChat Open Platform, your authorized nickname, profile picture and account identifiers such as OpenID and UnionID. Passwords are handled by the authentication provider (Firebase Authentication or Tencent Cloud); we never see them in plain text.
  2. Study data: word books, study and review records, learning progress and app settings (such as interface language and voice selection). This data is stored on your device only by default; if you sign in and enable cloud sync, it is synced to the cloud so it stays consistent across devices.
  3. Feedback: when you submit a content-correction report we collect the text you enter, the content category you select, the submission time, your account identifier, and the app version and platform type, so we can verify, reproduce and respond.
  4. Device and operational information: to keep the service stable and secure, our servers may record essential access logs such as access time, IP address, request path and error information.
  5. What we do not collect: contacts, precise location, photo library, microphone or recordings, biometric data, health data, financial account information, or advertising identifiers. The app includes no advertising or behavioural-analytics SDKs and does not track you across apps.

3. How We Use Information

  1. To provide core features: account sign-in, cloud sync of study data, and handling of content feedback (necessary to perform our contract with you);
  2. To keep the service secure, diagnose failures and prevent abuse (our legitimate interests, using measures with minimal impact on you);
  3. To comply with legal obligations and lawful requests from regulators;
  4. Where a specific processing activity requires your consent, we will ask for it separately. You may withdraw that consent at any time; withdrawal does not affect processing carried out before withdrawal.

4. AI-Generated Audio

All pronunciation in the app is produced by artificial-intelligence text-to-speech (TTS) technology. It is not a human recording and contains no user's real voice.

Pronunciation for some Chinese single characters, syllables and example sentences is pre-generated audio bundled with the app. It was generated during development using third-party cloud AI text-to-speech services (Volcengine Doubao Speech Synthesis and Alibaba Cloud Qwen-Audio TTS). That generation happened only at build time and processed dictionary and grammar text only; it involved no user's personal information or voice data. The app does not call these cloud services during normal use.

All remaining text is synthesized locally on your device by built-in offline AI models. The synthesis does not use the network, and neither the audio nor the source text is uploaded to our servers.

The app does not use the microphone, does not collect voice input, and does not record, upload or analyse your voice. If we ever add a feature that needs voice input, such as speech recognition, we will update this policy first and obtain your separate consent.

5. Storage Location and International Transfers

  1. Mainland China version: account and sync data are stored on Tencent Cloud (CloudBase / cloud database) within the territory of the People's Republic of China.
  2. Overseas version: sign-in and cloud sync are provided by Firebase (Firebase Authentication and Cloud Firestore) operated by Google LLC. Data may be transferred to and stored in the United States or other countries where Google operates data centres.
  3. Transfer safeguards: we rely on applicable mechanisms such as the EU Standard Contractual Clauses (SCCs) and the EU-US Data Privacy Framework (DPF), and require recipients to provide protection no less protective than described in this policy.
  4. You can contact us at the email address below to obtain details of these safeguards or a copy of the relevant clauses.

6. Retention

  1. Account and cloud sync data: retained while your account exists. After you delete your account we delete or anonymise it within 30 days; residual copies in backups are removed within 90 days as backups rotate.
  2. Feedback records: retained for 24 months after the issue is resolved, for follow-up and quality analysis.
  3. Server access logs: retained for 90 days.
  4. Local study data: stored on your device until you clear the app's data or uninstall the app.
  5. Where law requires a different retention period, that period applies.

7. Sharing and Third-Party Services

  1. We do not sell your personal information and do not use it for cross-app tracking or advertising.
  2. To provide essential features we use the following third-party services. They access information only as necessary to provide their service and are bound by their own privacy policies and our agreements:
  3. Firebase Authentication / Cloud Firestore (Google LLC): account sign-in and cloud sync of study data for the overseas version;
  4. Google Sign-In (Google LLC): third-party sign-in for the overseas version;
  5. Sign in with Apple (Apple Inc.): third-party sign-in; you may hide your real email address;
  6. WeChat Open Platform SDK (Shenzhen Tencent Computer Systems Co., Ltd.): WeChat sign-in for the mainland China version;
  7. Tencent CloudBase (Tencent Cloud): cloud functions and cloud database for the mainland China version;
  8. Offline AI components (sherpa-onnx, ONNX Runtime, MeloTTS, Supertonic and others): run entirely on your device, with no network access and no data upload.
  9. We do not provide your personal information to any other third party except in the cases above, with your separate consent, or where required by law or a competent regulator.

8. Your Rights

  1. You have the right to access, correct, copy and delete your personal information, to withdraw consent, to restrict or object to processing, and to receive a structured, commonly used copy of your data where technically feasible.
  2. You can delete your account and cloud data in the app via Settings - Delete Account; you can also sign out at any time, or clear the app's data to remove local data.
  3. You can manage the app's system permissions in your device settings.
  4. If you wish to exercise these rights and cannot do so in the app, contact us at the email address below. We will respond within 15 business days, or sooner where applicable law requires.
  5. You have the right to lodge a complaint with the data protection authority in your country or region (for example, your EU/UK supervisory authority, or the Cyberspace Administration or telecommunications regulator in mainland China).

9. Children

  1. The app is intended for general language learners and does not knowingly collect personal information from children.
  2. Mainland China: children under 14 should use the app only after a guardian has read and agreed to this policy.
  3. United States: children under 13 should use the app only with parental or guardian consent.
  4. EU/UK: users under 16 (or the lower age set by their member state, never below 13) should use the app only with guardian consent.
  5. If a guardian believes a child has provided personal information to us without consent, or wishes to access, correct or delete it, please contact us at the email address below.

10. Security

  1. We protect your information with HTTPS encryption in transit, access controls in the cloud, and sandboxed storage on your device. Authentication is handled by specialist providers and we do not store plain-text passwords.
  2. Access to data by our personnel is limited to what is necessary, and they are bound by confidentiality obligations.
  3. If a personal data breach occurs, we will notify you and report to regulators as required by applicable law.

11. Changes to This Policy

We may update this policy from time to time and will publish it through the app or the official website with the updated date. For material changes to the purposes, methods or types of information processed, we will notify you prominently, such as with an in-app notice; where the law requires it, we will obtain your consent again before the change takes effect.

12. Contact Us

If you have any question, comment or complaint about this policy or our handling of personal information, contact: qianyujie_app@163.com. We will handle it as soon as possible after verification, normally within 15 business days.