Privacy Policy

Introduction

Sand Nihongo is a mobile application published by Sandpia ("we," "our," or "us") that helps you learn Japanese for the JLPT (N5–N1). We are committed to protecting your privacy and being transparent about how your information is handled. This Privacy Policy explains what data the app processes when you use it.

Information We Process

Learning Data

Your study progress, statistics, and settings (such as levels completed and review history) are stored locally on your device. This data is not transmitted to our servers.

Handwriting Input

When you practice writing kanji or kana, your handwriting is recognized on your device using on-device machine learning. Handwriting input is processed in real time and is not recorded, stored, or transmitted.

Audio Pronunciation Files

To play word and character pronunciation audio during lessons, the app downloads audio files from our own servers. These requests are not linked to your device, advertising ID, account, name, or study content. As with any internet connection, your device's IP address is visible to our server when these requests are made.

Advertising

Sand Nihongo shows ads through Google AdMob, which may work with mediation partners such as Meta Audience Network. To show and measure ads, these partners use your device's advertising identifier (the IDFA on iOS or Advertising ID on Android) together with technical information such as device model, operating system version, and general (non-precise) region. We do not share your name, email address, or study content with these partners.

You can control ad personalization at any time:

• iOS: Choose "Ask App Not to Track" or "Allow" when prompted, or change your choice later in Settings > Privacy & Security > Tracking.
• Android: Opt out of interest-based ads or reset your advertising ID in Settings > Google > Ads.
• EEA, UK, and Switzerland: The device-level controls above apply here as well, and our advertising partners may limit ad personalization under their own policies. You can also contact us to opt out.

Analytics

We use Firebase Analytics to understand how the app is used (for example, which features or lessons are opened) so we can improve it. Analytics is turned off by default — we collect this data only if you choose to enable it in the app's Settings > Privacy section. When enabled, analytics data is tied to an app-instance identifier, not your name, email address, or study content. You can turn it off again at any time.

Diagnostics & Crash Reports

We use Firebase Crashlytics to collect diagnostic and crash data, such as device model, operating system version, and crash logs, to help us find and fix problems. Crash reporting is turned off by default — we collect this data only if you choose to enable it in the app's Settings > Privacy section. When enabled, this data is not linked to your name or account. You can turn it off again at any time.

In-App Purchases

Sand Nihongo offers in-app purchases that remove the periodic ad breaks and allow the voice files to be downloaded for offline study — a one-time lifetime purchase and an auto-renewable monthly subscription. Purchases and subscriptions are processed by the Apple App Store or Google Play. We do not receive or store your payment card details or billing address.

Your purchase is checked through the App Store or Google Play on your device, and the result is stored locally on your device — your entitlement status (whether ads are removed and whether a subscription is active), together with the transaction identifiers the store returns. We never receive this data, and it is removed when you uninstall the app.

If you have turned analytics on in the app's settings, the app also records that a purchase screen was shown and that a purchase was completed, together with the product identifier and its price, as an analytics event. This is not linked to your name, email address, or payment details, and nothing is recorded if analytics is left turned off. See Terms of Use for the purchase and subscription terms themselves.

How We Use Information

The data described above is used exclusively for the following purposes:

• Providing and saving your learning progress on your device
• Recognizing your handwriting during writing practice
• Downloading lesson pronunciation audio from our servers
• Displaying and measuring advertisements
• Understanding app usage and improving the app (Analytics)
• Diagnosing crashes and improving app stability

Third-Party Services

Sand Nihongo uses the following third-party services, each governed by its own privacy policy:

• Google AdMob (advertising)
• Meta Audience Network (advertising mediation)
• Firebase Analytics (usage analytics)
• Firebase Crashlytics (crash reporting)

These services may receive your device's advertising identifier and other technical or usage data as described above. We do not share your name, email address, or study content with them.

Data Retention

Learning data is stored only on your device and remains there until you clear it or uninstall the app.

Data Security

We rely on the security features built into your device's operating system and our service providers' infrastructure to help protect data. No method of storage or transmission is completely secure, but we take reasonable steps appropriate to the limited data the app processes.

International Data Transfers

Our service providers (Google and Meta) operate globally, so data such as advertising identifiers or analytics data may be processed in countries other than your own, including the United States. These providers participate in recognized international data transfer frameworks, such as the EU Standard Contractual Clauses, to help protect data sent across borders.

Your Privacy Rights

Most of the data Sand Nihongo processes — your learning progress and settings — is stored only on your device, so you can view, change, or delete it directly through the app or by uninstalling it. For anything else described in this policy, you can contact us at [email protected] to ask us to access, correct, or delete information we hold about you.

California Residents

Sharing your advertising identifier with our advertising partners for personalized ads may be considered a "sale" or "share" of personal information under California law. You can opt out at any time by:

• Declining App Tracking Transparency permission on iOS, or turning off ad personalization in your Android device's Ads settings
• Contacting us at [email protected] to request that we stop sharing your information with advertising partners

Children's Privacy

Sand Nihongo is intended for a general audience. We do not knowingly collect personal information from children under 13 years of age.

Changes to This Policy

We may update this Privacy Policy from time to time. We will notify you of any changes by posting the new Privacy Policy on this page and updating the "Last updated" date.

Contact Us

Sand Nihongo is published by Sandpia, which is the controller for the data it processes as described in this Privacy Policy. If you have any questions, please contact us at:

[email protected]