Fillorin

Privacy Policy

Last Updated: July 6, 2026

Fillorin ("we", "our", or "us") operates the Learn Japanese Android application. This Privacy Policy explains what data we collect, why we collect it, how it is stored and synced, and how you can delete it.

By creating an account or using Learn Japanese, you agree to the practices described in this policy.

1. What Data We Collect

We collect only what is needed to run the app and keep your progress safe across devices.

Account information: When you sign in (via Google or email), we receive your email address and an ID that identifies your account. We never see or store your password — sign-in is handled entirely by Google.
Study progress: Your learning activity, including vocabulary, kanji drawing, and reading. This is kept on your device and securely backed up to your private cloud account (Google Firebase) when you are online.

We do not collect your name, phone number, precise location, or any payment information.

2. How Your Progress Is Synced

Your study data lives primarily on your device. When the app is online, it backs up your progress to your private cloud account so it's available if you switch devices or reinstall.

When sync happens: Your progress is synced when you minimise or close the app. Only what has changed since the last sync is uploaded, which keeps data usage low.
Offline use: If there is no internet connection, the app continues working fully from your device. Your data will sync the next time a connection is available.
Data isolation: Your synced data is tied to your own account, and no other user can access your records.

3. App Integrity, Versioning & Maintenance

To keep the app secure and working correctly, Learn Japanese communicates with our secure backend (operated for us by Cloudflare). This service:

Verifies the app is a genuine, untampered build.
Checks that you are running a supported version, and flags outdated versions.
Signals planned maintenance windows.
Loads the app's study content and configuration.

These checks transmit only your app's version code and a security token — no personal information and no learning data is sent.

4. Third-Party Services

Learn Japanese uses the following external services to function:

Google Firebase — handles secure sign-in and the cloud backup of your progress. Firebase Privacy Policy ↗
Firebase Analytics — collects anonymous, aggregated usage data (e.g. which study modes are used) and retention, not tied to your identity, to help us improve features. Firebase Privacy Policy ↗
Firebase Crashlytics — collects crash and error reports, with device and OS details (not your identity), so we can diagnose and fix problems. Firebase Privacy Policy ↗
Firebase Performance Monitoring — measures app start-up time and responsiveness so we can keep the app fast. Firebase Privacy Policy ↗
Cloudflare — operates our backend used for app-integrity and security checks, version & maintenance gating, and loading study content (see Section 3). Cloudflare Privacy Policy ↗
Google ML Kit — powers on-device handwriting recognition and translation. Your drawings are processed entirely on your device and are never sent to our servers. ML Kit Terms ↗
Tatoeba — example sentences are loaded on demand from tatoeba.org; your device's IP address is shared with Tatoeba only when fetching a sentence.
Google AdMob — serves ads in the free version of the app (see Section 5). Google Privacy Policy ↗

You can turn off all analytics, crash reporting, and performance diagnostics at any time in Settings → About & Legal → "Share anonymous diagnostics." In the EEA, UK, and Switzerland this collection is additionally gated by your consent choice.

Aside from the anonymous, aggregated analytics described above, we do not use data brokers, and we never sell your personal data or share it with third parties beyond the services listed here.

5. Advertising

The free version of Learn Japanese is supported by advertising, served by Google AdMob. Ads appear only between study activities — never during writing practice, reviews, or quizzes.

What AdMob collects: to serve and measure ads, Google may collect your device's advertising ID, IP address, and general device information, as described in the Google Privacy Policy and How Google uses data from partner apps.
Your consent (EEA, UK & Switzerland): before any personalized ads are shown, you will see a consent message and can choose non-personalized ads instead. You can change your choice at any time from the app's settings.
Your controls: you can reset or delete your advertising ID at any time in Android Settings → Privacy → Ads.

We never share your learning data or account information with advertisers.

6. Deleting Your Account and Data

You are in full control. The fastest way to delete your data is directly inside the app via Settings → Account → Delete Account — it is instant and requires no waiting. If you can no longer access the app, you can permanently delete your account and data from our Data Deletion page, or request a full copy of it from our Data Export page.

Delete your account in-app (preferred): Open the app and go to Settings → Account → Delete Account. This immediately removes all your synced progress from the cloud and permanently deletes your account. There is no waiting period and no data is retained after deletion.
Request deletion or export from the web: If you cannot access the app, use the self-service forms on our Data Deletion page or Data Export page. Enter your registered email and we'll send a verification link to confirm the request is yours. Deletion permanently removes your account and data; export sends you a full copy of it. Both are processed within 7 working days, with a final confirmation email when complete.
Local data: Uninstalling the app removes the app's data from your device. If you have already deleted your account before uninstalling, all copies of your data — both local and cloud — will be gone.

7. Data Retention

We retain your data for as long as your account exists. If you delete your account, all associated data is deleted immediately from our systems. We do not keep backups of deleted user data.

8. Children's Privacy

Learn Japanese is a language-learning app suitable for a general audience. We do not knowingly collect any personal data beyond what is described in this policy. The app's built-in dictionary (JMdict) is a comprehensive Japanese–English reference and may contain vocabulary covering a broad range of topics. Parents or guardians should use their own discretion regarding app usage for younger children. If you have concerns about a child's account or data, please contact us and we will address it promptly.

9. Open-Source Licenses

Learn Japanese is built on outstanding open-source projects. Their licenses are reproduced in full below as required by their terms.

JMdict & KANJIDIC — Electronic Dictionary Research and Development Group CC BY-SA 4.0

This app uses the JMdict and KANJIDIC dictionary files, which are the property of the Electronic Dictionary Research and Development Group (EDRDG) and are used in conformance with the Group's licence.

Full license terms: http://www.edrdg.org/edrdg/licence.html ↗
CC BY-SA 4.0 summary: https://creativecommons.org/licenses/by-sa/4.0/ ↗

KanjiVG — Ulrich Apel CC BY-SA 3.0

Kanji stroke-order SVG data is sourced from KanjiVG, created by Ulrich Apel.

Full license terms: https://creativecommons.org/licenses/by-sa/3.0/ ↗

Typefaces — Klee One, Noto Sans JP, Noto Serif JP & Zen Maru Gothic OFL 1.1

Japanese text in the app is rendered using the following open-source typefaces, each distributed under the SIL Open Font License, Version 1.1:

Klee One — © The Klee Project Authors (github.com/fontworks-fonts/Klee)
Noto Sans JP & Noto Serif JP — © The Noto Project Authors (github.com/notofonts/noto-cjk)
Zen Maru Gothic — © The Zen Maru Gothic Project Authors (github.com/googlefonts/zen-marugothic)

License: SIL Open Font License, Version 1.1
Full license text: https://openfontlicense.org ↗

Key terms: the fonts may be freely used, embedded, and redistributed with software. They may not be sold on their own, and any modified version must be released under the same OFL 1.1 license.

10. Policy Updates

We may update this Privacy Policy from time to time. When we do, we will revise the "Last Updated" date at the top of this page. We encourage you to review this page periodically. Continued use of the app after changes constitutes acceptance of the updated policy.

11. Contact Us

If you have any questions about this Privacy Policy or your personal data, please contact us:

support@fillorin.com