Privacy Policy

This Privacy Policy explains how Ruminski Labs OÜ ("we," "us," or "our") collects, uses, and protects your personal data when you use the Tangoo app (the "App"). Tangoo is a Japanese learning app designed to help you learn Japanese through an offline-first dictionary, word lists, customizable tests, short stories and more.

To enhance your learning experience and improve our services, Tangoo integrates certain features that process data, including Firebase Analytics and Crashlytics. These tools help us understand how the app is used, identify issues, and improve functionality. Additionally, Tangoo offers optional features like User Accounts, Subscriptions, and Cloud Backups, which require processing additional user data. This Privacy Policy explains what data we collect, how it is used and stored, and your rights regarding your personal information.

1Who We Are

The App is operated by Ruminski Labs OÜ, a private limited company registered in Estonia, at Sepapaja tn 6, 15551 Tallinn, Estonia. We are the data controller for the personal data described in this policy. As an Estonian company, we process personal data in line with the EU General Data Protection Regulation (GDPR). Privacy contact: support@tangoo.dev.

2Information We Collect

Tangoo is designed to provide an offline-first learning experience. However, to enhance your experience and improve the app, certain features require the collection and storage of data. Below, we explain what data is collected, how it is used, and where it is stored.

Data Collected Locally

The following data is stored only on your device and is not transmitted to our servers or third-party services unless you create a user account:

• Dictionary: The entire Japanese dictionary data is saved locally in a database on your device.
• Word Lists: You can create custom word lists and assign words to them. This data is saved locally on your device.
• Grammar Favorites: You have the option to mark grammar items as favorites. These preferences are stored on your device.
• Test Data: Any test settings, progress or performance data from spaced repetition tests is stored locally to enhance your learning experience.

Data Collected Online

Certain features require data to be stored online using Firebase and our subscription provider:

• User Accounts: If you create an account, we collect your email address to enable authentication via Firebase Auth. This is required for optional features like Subscriptions and Cloud Backups.
• Subscription Data: If you subscribe to Tangoo Premium, we store purchase verification details (such as purchaseDate, purchaseToken, and platform) to verify your subscription status. These details are processed and managed using Google Firebase (Firestore) and our subscription provider, RevenueCat. This data is used solely for subscription verification and access management. We do not share it with third parties outside of Firebase, RevenueCat, and the app store (Google Play or the Apple App Store).
• User Feedback: Tangoo allows users to submit feedback to help improve the app. Feedback is collected anonymously and does not include any personally identifiable information. Submitted feedback is stored securely in our database and may be reviewed to enhance Tangoo's features. By submitting feedback, you agree that we may analyze and use it to improve our services.

Analytics Data

To improve Tangoo, we use Firebase Analytics to collect non-personal usage data. This includes:

• Feature usage (e.g., which pages are accessed).
• Device information (e.g., operating system, device model, and app version).
• Session data (e.g., session duration and frequency of use).

This data is aggregated and anonymized and is used to understand how users interact with the app and prioritize improvements. Firebase Analytics runs automatically for all users and is not tied to any personally identifiable information unless you create an account.

Crash Reporting

Firebase Crashlytics is used to identify and fix bugs or technical issues in Tangoo. When a crash occurs, Crashlytics collects technical data, including:

• Device information (e.g., operating system, app version).
• Crash logs and stack traces.
• Information about the actions leading to the crash.

This data helps us improve the app's stability and functionality. Crashlytics does not collect personally identifiable information unless it is manually tied to a user account (e.g., for premium users reporting issues).

Subscription Data

If you purchase a Premium Subscription, we store certain data to verify and manage your subscription. This includes:

• order id – A unique id from the app store (Google Play or the App Store) used to identify the order.
• product id – An identifier of the product that was purchased.
• purchase token – A unique token from the app store (Google Play or the App Store) used for subscription verification.
• platform – The operating system (Android or iOS) where the purchase was made.
• expiry date – The expiry date of the currently active subscription.
• purchase date – The date the subscription was purchased or renewed.

This data is used to confirm active subscriptions, grant premium access, and prevent fraud. Subscriptions are managed through RevenueCat, which receives your purchase identifiers and subscription status to determine your entitlement to premium features. Tangoo does not store or process payment information — all payments are handled by the app store (Google Play or the Apple App Store).

3How and Why We Use Your Data, and Our Legal Bases

We use your data for the following purposes, each with a legal basis under the GDPR:

• To provide the App and your account, sync and back up your data, and deliver any subscription you purchase — legal basis: performance of a contract.
• To keep the App secure, prevent fraud and abuse, diagnose crashes, understand and improve how the App is used, and respond to your feedback and requests — legal basis: our legitimate interests, and your consent where required for analytics and crash reporting.
• To comply with legal obligations, such as tax and accounting for purchases — legal basis: legal obligation.

We do not sell your personal data, we do not use it for third-party advertising, and we do not make decisions about you based solely on automated processing.

4User Accounts and Subscriptions

Creating a user account in Tangoo is optional, but it is required to access certain features, such as Premium Subscriptions and Cloud Backups. Below, we explain what data is collected, how it is used, and your responsibilities as a user.

Purpose of User Accounts

User accounts enable access to the following features:

• Premium Subscriptions: Allows users to unlock premium features, such as advanced tests and the Short Stories library.
• Cloud Backups: Provides the ability to securely back up your local data (e.g., Word Lists and Spaced Repetition scores) to the cloud, so it can be restored on other devices.

Data Collected During Account Creation

When you create an account, the following data is collected and processed through Firebase Authentication:

• Email Address: Used for account identification and authentication.
• Authentication Method: Whether you sign in using an email/password or via Google Login.

We do not collect any other personal information beyond what is required for authentication.

Password Recovery

If you forget your password for an email-based account, you can reset it directly in the app under Settings > Account > Reset Password. Alternatively, you can contact us at support@tangoo.dev for assistance. Note that we do not have access to your password.

User Responsibilities

You are responsible for maintaining the confidentiality of your login credentials. If you suspect unauthorized access to your account, please contact us immediately at support@tangoo.dev.

Account and Data Deletion

You can delete your account directly in the app under Settings > Account. Alternatively, you can contact us at support@tangoo.dev. Upon deletion, all associated online data (e.g., Cloud Backups) and your account data are permanently deleted, and premium access is revoked immediately. Offline data stored locally on your device is not affected and is removed when you uninstall the app or reset local data. Certain records may be retained for up to 7 years where required for tax, legal, or compliance purposes; after this period, they are permanently deleted.

Subscription Data Retention

If you cancel your subscription but do not delete your Tangoo account, we retain your subscription data for continued premium access until the end of your billing cycle. If you delete your Tangoo account, all subscription data will be permanently deleted, and premium access will be revoked immediately. For compliance and fraud prevention, certain subscription records may be retained for up to 6 months after expiration but will not be used for tracking or marketing.

5Third-Party Services (Processors)

Tangoo uses the following third-party services to enhance functionality, improve the app, and ensure data security. Below is an overview of these services, the data they process, and why they are necessary.

Firebase Authentication

Purpose: Enables user account creation, login, and authentication using email/password or Google Login.

Data Collected: Email address; authentication method (e.g., email or Google Login).

Why We Use It: To securely manage user accounts and provide access to features like Premium Subscriptions and Cloud Backups.

Firebase Firestore (Database)

Purpose: Stores user account information, subscription verification data, and Cloud Backup data.

Data Collected: User account data (email and authentication method); subscription data (purchaseDate, purchaseToken, platform, and subscriptionStatus for verifying premium access).

Why We Use It: To securely store and manage user accounts and subscriptions while ensuring premium feature access. For users who don't create an account, we are not saving any data in Firestore.

Firebase Cloud Functions (Backend Processing)

Purpose: Processes backend logic such as verifying app store subscriptions and handling automated tasks.

Data Processed: Subscription verification — automatically checks whether a user has an active subscription using their purchaseToken.

Why We Use It: To enable secure, automated verification of subscriptions without requiring users to manually validate their purchases.

RevenueCat

Purpose: Manages your subscription entitlements — that is, determining whether you have an active Premium subscription.

Data Collected: Purchase identifiers (such as your purchase token and product/order id), platform, and subscription status, together with an app-specific user identifier.

Why We Use It: To reliably verify purchases and unlock premium features across devices without handling your payment details ourselves. See the RevenueCat Privacy Policy.

Firebase Analytics

Purpose: Tracks app usage to help us understand user behavior and improve Tangoo's features.

Data Collected: App usage data (e.g., screens accessed, session duration); device information (e.g., OS version, device model).

Why We Use It: To analyze which features are most used and identify areas for improvement.

Opt-Out Option: You can disable Analytics at any time in the app under Settings > Privacy.

Firebase Crashlytics

Purpose: Monitors app performance and identifies technical issues or crashes.

Data Collected: Crash logs and stack traces; device information (e.g., OS version, app version).

Why We Use It: To diagnose and resolve crashes, ensuring the app runs smoothly for all users.

Opt-Out Option: You can disable Crash Reports at any time in the app under Settings > Privacy.

App Stores (Google Play & Apple App Store)

Purpose: Facilitates subscription payments and manages premium feature access.

Data Collected: The app store you download Tangoo from (Google Play or the Apple App Store) collects payment information and processes transactions. Tangoo does not store or process your financial information.

Why We Use It: To securely handle payments for Premium Subscriptions and manage subscription statuses. You can learn more in the Google Privacy Policy and the Apple Privacy Policy.

Data Sharing with Third Parties

The data shared with Firebase, RevenueCat, and the app stores (Google Play and the Apple App Store) is necessary to provide the services outlined above, and these providers comply with strict security and privacy standards. For more information on Firebase's data handling practices, you can review the Firebase Privacy Policy and Firebase Terms of Service.

6International Transfers

Some of our service providers — for example, Google (Firebase) and RevenueCat — may process data outside the European Economic Area (EEA), including in the United States. Where that happens, the transfer is protected by appropriate safeguards, such as the European Commission's Standard Contractual Clauses. You can ask us for more information by emailing support@tangoo.dev.

7Security

Tangoo takes data security seriously and implements measures to protect your personal information and user data. For features like User Accounts and Cloud Backups, data is stored and processed through Firebase, which complies with industry-standard security protocols, including encryption during data transmission and storage.

While Firebase provides secure infrastructure, we recommend users take the following precautions to enhance security:

• Use strong, unique passwords for your account.
• Keep your login credentials confidential.
• Secure your device with a password, biometric lock, or similar measures.

If you suspect unauthorized access to your account or data, please contact us immediately at support@tangoo.dev.

8Your Rights

Under the GDPR, you have the right to: access the personal data we hold about you; correct inaccurate data; delete your data (the "right to be forgotten"); restrict or object to processing; data portability; and withdraw consent at any time, without affecting processing already carried out. You can exercise many of these rights directly in the App — including deleting your account (Settings > Account) and turning analytics and crash reporting on or off (Settings > Privacy) — or by emailing support@tangoo.dev. We will respond within the time the law allows. You also have the right to lodge a complaint with your local data-protection authority; in Estonia this is the Estonian Data Protection Inspectorate (Andmekaitse Inspektsioon, www.aki.ee).

9California Residents

If you are a California resident, you have rights under the CCPA/CPRA to know what personal information we collect, to request its deletion, and to opt out of any "sale" or "sharing" of personal information. We do not sell or share your personal information. You can exercise these rights using the contact details above, and we will not discriminate against you for doing so.

10Children's Privacy

Tangoo is suitable for users of all ages. However, we do not knowingly collect personal information from children under the age of 13 without parental consent. For optional features like User Accounts and Subscriptions, users must be at least 13 years old to comply with applicable privacy laws.

If you are a parent or guardian and believe your child has provided us with personal information without your consent, please contact us at support@tangoo.dev. Upon verification, we will promptly delete any such data from our systems.

11Changes to This Privacy Policy

We may update our Privacy Policy from time to time. Since Tangoo is still in active development, future features might significantly impact what data we store and process. Any changes will be posted on this page with an updated effective date. We encourage you to review this Privacy Policy periodically for any changes.

12Contact Us

If you have any questions or requests regarding this Privacy Policy or your personal data, email us at support@tangoo.dev, or write to Ruminski Labs OÜ, Sepapaja tn 6, 15551 Tallinn, Estonia.