Lingo Diary Privacy Policy

Last Updated: May 6, 2026

Welcome to Lingo Diary (the "Service" or the "App"). This Service is provided by SPARKLECT CO., LTD. ("we", "us", or "our"). We take your privacy seriously. This Privacy Policy explains how we collect, use, disclose, and protect your information.

The App is designed to help users learn languages through AI-guided conversations and diary writing in their target language. By downloading or using the App, you agree to the practices described in this Privacy Policy.

1. Information We Collect

To provide AI conversation guidance, diary generation, and personalized language learning services, we may collect the following categories of information:

1.1 Information you provide

  • Account information: When you register, we may collect your email address, username, or third-party login credentials (such as Google or Apple ID) to create your account and sync data.
  • User content (text): Your text conversation messages with the AI, target language selection, native language settings, and language proficiency level.
  • User content (voice): If you use the voice message feature, the audio you record (AAC m4a format, up to 30 seconds per message) will be uploaded to Firebase Cloud Storage and sent to Google Gemini for speech transcription and pronunciation teaching analysis.
  • Usage and transaction records: Your in-app activity records (such as diary generation history, conversation records, ad-reward records, and points-deduction records) and subscription status.

1.2 Information collected automatically

  • Device information: Including device model, operating system version, IP address, language settings, and the following device identifiers:
    • IDFV (Identifier for Vendors): Apple's "same-vendor device identifier" used to recognize the same device across apps published by us, supporting account linkage and analytics.
    • IDFA (Identifier for Advertisers): Accessed by advertising SDKs only after you grant "Allow Tracking" via App Tracking Transparency (ATT), used for cross-app advertising measurement and attribution.
  • App Tracking Transparency (ATT): iOS will display a system prompt the first time the relevant feature is invoked, asking whether you allow the App to track your activity across other companies' apps and websites. Regardless of your ATT choice, the App's core functionality (chat, diary, voice, subscriptions) remains fully available. If you decline, advertising SDKs cannot access IDFA, but ads will still be shown (with potentially lower precision and relevance).
  • Usage data and analytics events: Through tools such as Firebase Analytics, we record how you interact with the App. This includes but is not limited to: features clicked, pages viewed, time spent, feature usage frequency, and crash reports (Crashlytics).

2. How We Use Your Information

We use collected information for the following purposes:

  • Core service delivery: Sending your text conversations and voice recordings to backend AI models (LLM) to generate personalized language learning feedback, diary content, voice transcripts, and pronunciation teaching.
  • Account management and sync: Using Firebase services to store your conversation records, diaries, voice recordings, and settings in the cloud, ensuring data synchronization across your devices.
  • Ad delivery and reward issuance: Showing advertisements (including rewarded ads) through third-party advertising SDKs, and recording your rewarded-ad completion events through the SDKs' Server-Side Verification (SSV) mechanism in order to issue permanent points rewards.
  • Analytics and product optimization: Using Firebase Analytics to analyze anonymized usage behavior. This helps us understand which features are most popular, identify usability bottlenecks, and improve the user interface and service quality.
  • Fair use and abuse prevention: Monitoring abnormal usage patterns and points-deduction records to operate dynamic risk-control mechanisms that prevent abuse.
  • Service improvement: Analyzing anonymized usage data to optimize AI generation accuracy and improve App performance.

3. Information Sharing and Third-Party Services

We do not sell your personal information to third parties. However, to operate the App, we share specific data with the following service providers:

3.1 AI technology providers

To provide personalized language learning guidance, diary generation, and voice teaching services, the App integrates third-party artificial intelligence models.

  • Recipients: Relevant data is sent to Google Gemini.
  • Data sent: Limited to your text conversations, voice recordings, target language, native language settings, and language proficiency level that you actively input.
  • Privacy commitment: We do not proactively send your name, email, phone number, precise device location, or any personally identifying information to AI providers.
  • Data security and compliance:
    • No-training policy: Per the provider's current API terms of service, data sent via the API is not used by default to train their foundational AI models.
    • Secure transmission: Our selected provider offers industry-standard encryption and security protections for API transmissions.
    • Temporary storage and deletion: Data is only temporarily stored on the provider's protected servers for safety review purposes (e.g., abuse prevention), with retention periods governed by their internal policies.

3.2 Cloud storage and infrastructure

  • Google Firebase: We use Firebase for authentication (Authentication), database storage (Firestore), file storage (Cloud Storage, including voice recordings), and data synchronization. Your data is securely stored on Firebase servers.

3.3 Analytics services

  • Google Analytics for Firebase (Firebase Analytics): We use this tool to collect anonymized usage behavior data. Google may use the collected data to analyze App usage patterns.

3.4 Advertising services

To support the operation of the free tier and to enable the "watch a rewarded ad to earn permanent points" feature, the App integrates third-party advertising SDKs, including both ad mediation platforms and ad networks.

  • Partners: The advertising SDKs we currently work with include but are not limited to AppLovin (MAX), Google AdMob, and other ad networks accessed through mediation platforms (such as Pangle, etc.). We may from time to time adjust our partners, the role each partner serves (for example, an ad network may become the mediation platform, or vice versa), and the way they are integrated, without individual prior notice. The most current and complete list of partners is the app-ads.txt file in the root of this website.
  • Rewarded-ad issuance: Upon completion of a rewarded ad, we use the Server-Side Verification (SSV) mechanism provided by the selected mediation platform: its server forwards the completion event to our server, and we then issue the corresponding permanent points.
  • Data collected: With ATT consent, the above advertising SDKs may collect IDFA, ad interaction events, device information, and coarse-grained location (estimated from IP) for ad delivery, frequency capping, and performance measurement. If you decline the ATT prompt, these SDKs cannot access IDFA but ads will still be shown (with lower precision). For each SDK's privacy practices and the details of data collection, please refer to its official privacy policy.

4. Subscriptions and Payments

The App offers subscription services. All transactions are processed through the App Store or Google Play payment systems. We do not collect or store your credit card or bank account information. We only receive transaction receipts returned by the app stores to verify your subscription status.

5. Data Security and Retention

  • Security: We use industry-standard encryption technologies (such as SSL/TLS) to protect your data during transmission and storage.
  • Data retention: We retain your data while your account remains active. If you choose to delete your account, we will permanently delete your personal information and related data (conversation records, diaries, voice recordings, settings, etc.) from our servers within a reasonable period.

6. Your Rights

Depending on your region, you have the following rights:

  • Access and correction: You may view and edit your data at any time in the settings page.
  • Tracking authorization management: You may change the App's ATT authorization status at any time via iOS "Settings > Privacy & Security > Tracking".
  • Account deletion: You can find the "Delete Account" option in the account management page of the App. Once executed, all your data (including unused points, voice recordings, conversations, and diaries) will be permanently deleted and cannot be recovered.

7. Children's Privacy

The App is not designed for children under 13 years of age (or the age specified by local law). We do not knowingly collect personal information from children. If we discover that we have inadvertently collected information from a child, we will immediately delete such information.

8. Changes to This Privacy Policy

We may update this Privacy Policy from time to time. Any changes will be posted on this page with the "Last Updated" date revised accordingly. For significant changes, we may notify you through an in-app notification.

9. Contact Us

If you have any questions about this Privacy Policy or our data handling practices, please contact us through the following:

  • Company name: SPARKLECT CO., LTD.
  • Email: service@sparklect.com