Privacy Policy
Effective as of May 29, 2026
Kanji Bird is an online language learning platform that lets you practice Japanese hiragana, katakana, and kanji through an interactive flashcard game. This Privacy Policy describes how Kanji Bird ("Kanji Bird", "we", "us", or "our") handles personal information collected through our website and any related applications (collectively, the "Service").
Contents
1. Personal Information We Collect
Information you provide to us
Personal information you may provide through the Service includes:
- Account data: your email address, display name, and password (or OAuth token if you sign in with Google). We use Firebase Authentication to manage accounts securely.
- Practice data: records of which cards you practiced, whether you answered correctly or missed, response times, and timestamps. This data powers your progress dashboard and spaced-repetition scheduling.
- Progress & preferences: which cards you have mastered, manual difficulty ratings you assign, spaced-repetition state (stability and difficulty per card), and which practice decks you have enabled.
- Custom decks: flashcard content you create yourself, including glyphs, answers, and hints you provide.
- Communications data: information you send when you contact us for support or feedback.
Automatic data collection
We and our service providers may automatically collect information about your device and interaction with the Service, such as:
- Device data: operating system, browser type, screen resolution, IP address, and general location (city/region level).
- Usage data: pages viewed, features used, session duration, and error logs.
Cookies and local storage
The Service uses browser local storage to save your practice state, enabled decks, and preferences locally on your device. We may also use session and persistent cookies for authentication and analytics purposes.
2. How We Use Your Personal Information
We may use your personal information to:
Service delivery
- Provide, operate, and improve the Service
- Create and maintain your account
- Sync your practice progress across devices when you are signed in
- Schedule flashcard reviews using spaced-repetition algorithms
- Display your progress and statistics on the dashboard and logs
- Send account-related notices such as security alerts
- Respond to your support requests and feedback
Research and development
We may use aggregated, anonymised practice data to analyse and improve the Service, including tuning spaced-repetition parameters and identifying common learning patterns. This analysis does not identify individual users.
Compliance and protection
- Comply with applicable laws and legal processes
- Protect the rights, privacy, and safety of our users and ourselves
- Prevent fraudulent or unauthorised activity
4. Your Choices
- Access or update your information: you may review and update your account information by signing in to your account.
- Delete practice data: you may clear your local practice logs and progress from within the app settings at any time.
- Account deletion: you may request deletion of your account and associated personal information by contacting us. Upon deletion, your account and personal data will be permanently removed within 30 days. Anonymised, aggregated usage statistics derived from your data may be retained.
- Local data: practice progress stored only in your browser's local storage can be cleared at any time through your browser settings.
5. Security
We employ technical and organisational safeguards to protect your personal information, including encrypted data transmission (HTTPS), Firebase security rules limiting data access to authenticated account owners, and regular security reviews. However, no internet or information system can be guaranteed to be completely secure, and we cannot warrant the absolute security of your information.
6. Data Retention
We retain your personal information for as long as your account is active or as needed to provide the Service. Specifically:
- Account information is retained while your account remains active.
- Practice logs and progress data are retained for up to 24 months of account inactivity, after which they may be archived or deleted.
- Upon account deletion, personal information is permanently deleted within 30 days. Anonymised aggregate data may be retained for service improvement purposes.
7. International Data Transfer
Kanji Bird uses cloud infrastructure (Firebase / Google Cloud) that may store and process your data in the United States or other countries. Privacy laws in those jurisdictions may differ from those in your country. By using the Service, you consent to the transfer of your information to these locations.
8. Children
The Service is not directed to children under 13 years of age. We do not knowingly collect personal information from children under 13. If you are a parent or guardian and believe we have inadvertently collected such information, please contact us and we will delete it promptly in accordance with applicable law.
9. Changes to this Privacy Policy
We may update this Privacy Policy from time to time. When we make material changes we will update the effective date at the top of this page. Your continued use of the Service after any update constitutes acceptance of the revised Privacy Policy.
10. How to Contact Us
If you have questions about this Privacy Policy or wish to exercise your data rights, please reach out via the feedback option within the app or through our website contact page.