**Last updated:** 2026-07-23
## Privacy Policy
This Privacy Policy explains how **Sennin — JLPT Japanese Vocab** (“**Sennin**”, “**we**”, “**us**”) collects, uses, and shares information when you use our mobile application (the “**App**”).
If you have questions, contact us at: **wintervaultstudio@gmail.com**
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## 1) Information we collect
### A) Account & authentication
- **Google Sign-In information** (basic profile data such as your Google account identifier and email, depending on what you approve) to authenticate you and associate your subscription status where applicable.
- If you use optional **Google Drive backup**, Sign-In may also request permission to create and manage backup files in the App’s private **Google Drive App Data** folder (not your full Drive).
### B) App content you create
- **Japanese vocabulary study data** you generate in the App, including decks, study progress, spaced-repetition scheduling, session history, and related preferences.
- This content is stored **primarily on your device** (local database).
### C) Purchases & subscriptions
- If you subscribe to Pro, we process **purchase/subscription information** via **Google Play Billing** (for example, purchase tokens and subscription status) to activate and maintain Pro features.
- If server-side verification is enabled, our **backend** may receive a **purchase token** and related subscription metadata to confirm entitlement. We do not use this to read your vocabulary or notes.
### D) Notifications (optional)
- If you enable study reminders, we may store your **notification preferences** (for example, which reminders are enabled and scheduling choices you set in the App).
### E) Backup / export (optional)
- **Device backup file:** If you use export, you may create a **JSON file** containing a snapshot of your local study data. That file is shared or stored **only where you choose** (for example, your device storage, email, or cloud storage you pick via the system share sheet).
- **Google Drive backup (optional):** If you **sign in with Google** and choose to, the App can save JSON backup copies in your **Google Drive App Data** folder (a private area used only by this App). You create, browse, restore, or delete those copies **explicitly in Settings** (for example, “Save copy to Drive” / “View Drive backups”). The App does **not** upload or overwrite Drive backups automatically when you sign in or while you study. We do **not** use these copies for advertising. The files live in **your** Google account under Google’s Drive terms.
### F) Crash logs, diagnostics, and performance (Sentry — optional)
- We use **Sentry** ([sentry.io](<https://sentry.io/>), Functional Software, Inc.) on **Android and iOS** native builds **when** a Sentry DSN is configured at build time (`EXPO_PUBLIC_SENTRY_DSN`) to collect **crash logs**, **diagnostics**, and limited **performance / tracing** data so we can fix bugs, improve stability, and understand slow paths. This may include stack traces, device and OS metadata, and app version information.
- We configure the SDK with **sendDefaultPii disabled** by default so we do not intentionally ask Sentry to attach extra personal identifiers beyond what may appear inside a technical error context.
- **Expo Go** and **web** builds do not initialize this SDK in our current setup.
- If no Sentry DSN is present in a given build, crash reporting may rely on **Google Play** developer reporting for store builds.
### G) Analytics (Firebase — Google)
- On **Android and iOS store / dev-client builds**, we use **Firebase Analytics** via the **native Firebase SDK** (`@react-native-firebase/analytics`, Google) to collect **app interaction events** and limited **usage statistics** (for example: onboarding completed, study session started or completed, paywall viewed, subscription activated, screen views, and retention milestones).
- Event parameters are **aggregated** (for example: JLPT level, study mode, session counts, app language). We do **not** intentionally send your email, name, studied vocabulary text, or free-form notes through Firebase Analytics.
- Firebase may process **device or app instance identifiers** as part of standard analytics. Google’s terms and privacy notice apply: [<https://firebase.google.com/support/privacy>](<https://firebase.google.com/support/privacy>).
- We also initialize the **Firebase JavaScript SDK** with project configuration keys for compatibility; **analytics events are sent through the native SDK**, not through the JavaScript analytics API in our current setup.
- **Expo Go** does not send native Firebase Analytics events.
### H) Other analytics (limited)
- Beyond Firebase Analytics and optional Sentry, we do not operate a separate first-party analytics backend for behavioral tracking.
- We do **not** intentionally collect sensitive personal information through analytics beyond what is described above.
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## 2) How we use information
We use information to:
- Provide core functionality (Japanese vocabulary study, decks, progress, and preferences).
- Authenticate you and protect the App.
- Provide Pro features and verify subscription status.
- Send optional reminders you enable.
- Let you create and restore optional backups you choose (device file and/or Google Drive App Data).
- Improve reliability, stability, and user experience (including through crash and performance telemetry and Firebase Analytics described above).
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## 3) Where your data is stored
- **On-device storage:** Most of your study data is stored locally on your phone.
- **Google Drive App Data (optional):** If you save a Drive backup in Settings, JSON copies are stored in the App’s private App Data folder in **your** Google Drive account (see section 1(E)). We do not host those files on our own servers.
- **Network requests:** Some features require internet access (for example, Google Sign-In, Google Play Billing, optional subscription verification, **optional Google Drive backup**, **Firebase Analytics** on native builds, **Sentry** telemetry on native builds when configured, and **Firebase** configuration endpoints). Data sent to our backend is used only to fulfill the request and operate the service.
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## 4) Sharing of information
We do not sell your personal information.
We share information only as needed with:
- **Google** (Google Sign-In; Google Play Billing for subscriptions; **Firebase Analytics** and Firebase configuration on native builds; **Google Drive** when you authorize Drive App Data backup, as described in section 1(E)).
- **Sentry** (Functional Software, Inc.) for crash reporting, diagnostics, and limited performance data on supported mobile builds when configured, as described in section 1(F). Their practices are described at [sentry.io/privacy](<https://sentry.io/privacy/>).
- **Service providers** that help us operate the App (for example, hosting for subscription verification) strictly for providing the service.
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## 5) Data retention
- **Local data:** Stays on your device until you delete it in-app or uninstall the App.
- **Google Drive App Data backups:** Remain in your Google account until you delete them in the App (Drive backups list) or through Google account / Drive controls that apply to App Data. Uninstalling the App does **not** always delete App Data files automatically.
- **Backend logs / processing:** We retain only what is necessary to operate and secure the service and comply with legal obligations.
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## 6) Your choices & controls
You can:
- Use the App without enabling optional features (such as reminders or Drive backup).
- Disable notifications anytime in device settings.
- Export or import a device backup file from Settings.
- Create, list, restore, or delete Google Drive App Data backups from Settings when signed in.
- Delete local app data by clearing the App’s storage or uninstalling.
- Request help about account-related questions by emailing **wintervaultstudio@gmail.com**.
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## 7) Children’s privacy
Sennin is not directed to children under 13, and we do not knowingly collect personal information from children.
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## 8) Security
We use reasonable safeguards to protect information. No method of transmission or storage is 100% secure.
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## 9) Changes to this policy
We may update this Privacy Policy. We will update the “Last updated” date above.
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## 10) Contact
Email: **wintervaultstudio@gmail.com**
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# Terms of Service (Sennin — JLPT Japanese Vocab)
**Last updated:** 2026-07-23
## 1) Acceptance of terms
By using Sennin, you agree to these Terms.
## 2) The service
Sennin provides tools to study **Japanese vocabulary** with a focus on **JLPT-oriented** learning. The App is an independent study aid and **does not** replace official JLPT registration, testing, or results. **JLPT** is a trademark of its respective owners; Sennin is not affiliated with or endorsed by those owners.
## 3) Accounts
If you sign in with Google, you are responsible for maintaining access to that account.
## 4) Optional backups
- Device JSON export/import and optional Google Drive App Data backups are tools you control. You are responsible for keeping copies you need and for granting or revoking Google Drive permissions.
- Restoring a backup can replace study data on the device. Review restore confirmations carefully.
## 5) Pro subscriptions
- Pro subscriptions are processed by **Google Play**.
- Pricing, trial terms (if offered), renewal, and cancellation are managed in your Google Play account.
- You can manage or cancel in Google Play’s subscription settings.
## 6) Acceptable use
You agree not to misuse the App, interfere with its operation, or attempt unauthorized access.
## 7) Intellectual property
The App and its content (including software and bundled materials) are owned by us or our licensors. You may not copy or redistribute the App except as permitted by law.
## 8) Disclaimer
Sennin is provided “as is” without warranties. We do not guarantee uninterrupted or error-free operation. Study outcomes depend on your effort; we do not guarantee exam results.
## 9) Limitation of liability
To the maximum extent permitted by law, we are not liable for indirect, incidental, or consequential damages.
## 10) Termination
You may stop using the App at any time. We may suspend or terminate access if required to protect the service or comply with law.
## 11) Contact
Questions about these Terms: **wintervaultstudio@gmail.com**