Duolian Privacy Policy

1. How we collect and use your personal information

Personal information means information recorded electronically or otherwise that can identify a natural person, either on its own or together with other information, or that reflects a natural person's activities. We collect and use your personal information only for the purposes described in this policy.

(1) Information required for core business functions

Our core business function is to provide badminton movement comparison and correction guidance. To deliver that function, we may collect and use the following information:

1. Account registration and sign-in: You can sign in with Apple, Google where available, or a mobile phone verification code. Depending on your chosen method and authorization, we receive the sign-in provider’s account identifier, name or email address (which may be an Apple relay address), or verify your phone number with an SMS code. We assign an account identifier to associate training records and membership entitlements. We do not receive your Apple or Google password.
2. Technique comparison analysis:
   • Video you upload: To compare movement, you need to upload badminton videos you recorded yourself. Those videos may include your image, movement posture, and other personal information, and may even contain sensitive personal information. Make sure the uploaded material belongs to you or has been fully authorized, and avoid capturing unrelated people or sensitive scenes where possible.
   • Pose keypoint data: We may use third-party or in-house technology to process uploaded video and extract pose skeleton keypoint data in order to complete motion matching and analysis.
   • Device information: To adapt the service, protect quality of operation, and maintain security, we may collect hardware and software characteristics such as device model, operating system version, device settings, and unique device identifiers.
   • Log information: When you use the service, we may automatically collect network logs such as IP address, browser type, carrier, language, access time, and page visit records.
   • Payment and billing information: When you purchase a Starter Pack, subscribe on the website, or request a refund, we and our authorized payment partners, such as Paddle, may collect the billing email, country or region, order identifier, tax information, payment status, and other transaction metadata needed for fraud checks and reconciliation. We do not store full bank card numbers or full card credentials ourselves.
3. iOS subscriptions and purchase history: Apple processes App Store payments, and RevenueCat provides receipt validation and subscription management. We and RevenueCat process your Duolian account identifier, product identifiers, transaction and original transaction identifiers, purchase and expiration dates, renewal or refund status, and necessary store and transaction environment information. We use this account-linked data to grant and synchronize membership, restore purchases, prevent duplicate grants, reconcile transactions and analyze subscriptions. We do not use it for cross-app or cross-website advertising tracking. This does not give us your full card number, bank account or Apple account password. Deleting your Duolian account does not cancel an Apple subscription; manage or cancel it in Apple’s subscription settings. Apple and RevenueCat process their service data under their respective privacy policies.
4. Customer support and issue reports: When you voluntarily report an app issue, we collect the description you enter, a contact email where applicable, an account identifier, and the minimum diagnostics needed to investigate, such as the app version, operating-system version, device model, language and time zone, current feature screen, and device connection state. You can choose whether to include a screenshot of the current screen, which may contain personal information visible on that screen. A screenshot is uploaded only after you enable the option and send the report, and it is not saved to Photos. We use this information only to review, respond to, diagnose, and improve the issue you reported.

(2) Improving our products and services

1. Model optimization: After anonymization or de-identification, we may use your uploaded video data, pose keypoint data, and analysis result data to train and improve our algorithm models. This data is used only to improve Duolian functions and user experience.
2. Statistics and analysis: We may aggregate and anonymize device information, logs, usage frequency, and feature usage patterns for analytics and product optimization.
3. Personalized recommendations (optional): We may recommend standard videos, training courses, or features based on your habits and preferences. If we introduce this in the future, you will be able to turn it off in the app.
4. Security protection: We may use information for identity verification, fraud monitoring, security prevention, archiving, and backup to keep the service secure and stable.

(3) Exceptions that do not require consent

Under applicable laws and regulations, we may collect personal information without your separate authorization in the following circumstances:

1. When it relates to national security or defense security.
2. When it relates to public security, public health, or major public interests.
3. When it relates to criminal investigation, prosecution, trial, or enforcement of judgments.
4. When it is necessary to protect your or another person's life, property, or other major lawful interests and obtaining consent is difficult.
5. When the personal information has already been made public by you.
6. When it is collected from lawfully public sources.
7. When it is necessary to sign or perform a contract at your request.
8. When it is necessary to maintain the secure and stable operation of products or services.
9. Other situations required by laws and regulations.

2. Cookies and similar technologies

To keep the service operating normally, we may store small data files called cookies on your device or use similar technologies. Cookies help us store preferences and related data. We do not use cookies for purposes outside this policy. You may manage or delete cookies based on your own preferences.

3. Sharing, transfer, and public disclosure of personal information

(1) Sharing

We do not share your personal information with companies, organizations, or individuals outside Duolian service providers, except in the following situations:

1. Sharing with your explicit consent: After obtaining your explicit consent, we may share your personal information with other parties.
2. Sharing required by law: We may share personal information as required by laws and regulations, dispute resolution needs, or lawful requests from administrative or judicial authorities.
3. Sharing with authorized partners:
   • Some services may be provided jointly by us and authorized partners solely for the purposes described in this policy.
   • For example, we need to share your mobile phone number with an SMS service provider to send verification codes, and we may use a third-party technical service provider to process video data and extract pose keypoints.
   • When you complete a website payment, we may also share billing email, order identifier, country or region, and required transaction metadata with payment processors, tax calculation providers, or fraud prevention partners to charge the order, issue refunds, and review payment risk.
   • We share only the personal information necessary to deliver the service, and we require partners to process that information under data processing agreements and security requirements.

(2) Transfer

We do not transfer your personal information to any company, organization, or individual except in the following situations:

1. When we obtain your explicit consent.
2. When a merger, acquisition, or bankruptcy liquidation requires transfer of personal information, in which case we will require the new holder to continue to be bound by this policy or to seek your authorization again.

(3) Public disclosure

We disclose your personal information publicly only in the following situations:

1. When we have your explicit consent or based on your active choice.
2. When laws, legal process, litigation, or governmental authorities compel the disclosure.

(4) Exceptions that do not require prior consent

The following situations do not require prior authorization for sharing, transfer, or public disclosure:

1. When it relates to national security or defense security.
2. When it relates to public security, public health, or major public interests.
3. When it relates to criminal investigation, prosecution, trial, or enforcement of judgments.
4. When it is necessary to protect your or another person's life, property, or other major lawful interests and obtaining consent is difficult.
5. When the personal information has already been made public by the data subject.
6. When it is collected from lawfully public sources.
7. Other situations required by laws and regulations.

4. How we store and protect your personal information

(1) Storage

1. Storage location: Personal information collected and generated during operations in the People's Republic of China will be stored within China.
2. Retention period: We retain personal information only for as long as necessary to fulfill the purposes described in this policy, unless a longer retention period is required by law. Uploaded videos and related pose data will be deleted or anonymized after you delete them, close your account, or after service completion when storage is no longer necessary, except for anonymized data already used for model improvement. Records used for verification-code checks are cleaned up regularly after verification is completed or expires.

(2) Protection

1. We have implemented reasonable and industry-standard safeguards to prevent unauthorized access, disclosure, use, alteration, damage, or loss of personal information.
2. We take reasonable steps to avoid collecting irrelevant personal information.
3. The internet is not completely secure, and we will do our best to protect any information you send to us.
4. If a personal information security incident occurs, we will notify you and report to regulators as required by applicable law.

5. Your rights

Under applicable Chinese laws, regulations, standards, and common practices in other countries and regions, we protect the following rights over your personal information:

1. Access: You may access your personal information through visible product entry points or by emailing support@duolian.cc.
2. Correction: If you discover errors in the personal information we process, you may request correction by contacting support@duolian.cc.
3. Deletion: Within the scope allowed by law, if our processing violates laws, regulations, or our agreement with you, or if you no longer use our products and services, you may request deletion.
4. Changing the scope of consent: For personal information collected beyond what is necessary, you may withdraw consent at any time by email. Withdrawal does not affect prior processing based on your authorization.
5. Account closure: You may contact support@duolian.cc to request account deletion. After closure, we will stop providing the service and delete or anonymize personal information according to your request.
6. Response timeline: To protect security, we may ask you to verify your identity. In general, we respond within fifteen business days.

6. How we handle children's personal information

This app is suitable for users aged 4 and above. For child users, which under Chinese law means minors under 14 years of age:

• Children should use the app under the guidance of parents or guardians.
• Account registration for children should be completed by parents or guardians, or under their supervision.
• We collect, use, or disclose children's information only where permitted by law, explicitly consented to by parents or guardians, or necessary to protect the child.
• If we discover that we collected a child's personal information without verifiable parental consent, we will delete the related data as soon as possible.

7. How this policy may change

Our privacy policy may change from time to time. Without your explicit consent, we will not reduce your rights under this policy. We will publish any updates on this page and provide more prominent notice for material changes.

Material changes include, but are not limited to:

1. Major changes to service models, such as the purpose, type, or method of processing personal information.
2. Major changes in control, such as changes of ownership caused by merger or restructuring.
3. Major changes to the main recipients of shared, transferred, or publicly disclosed personal information.
4. Major changes to your rights involving personal information processing or the way those rights are exercised.
5. Changes to the responsible department, contact methods, or complaint channels for personal information security.
6. High-risk findings in personal information security impact assessments.

8. Contact us

If you have any questions, comments, or suggestions about this privacy policy, or if you want to exercise your personal information rights, contact us here: