Privacy Policy

1. What this policy covers

This policy explains how Keisan Cards accesses, uses, stores and shares data obtained through Google APIs. The app is operated by Hidenobu Nagai for his own personal use and for a small number of people he knows personally. It is not a commercial service.

2. Google user data the app accesses

The app acts on the Google Account that authorized it. It requests these Google OAuth scopes:

• openid
• email
• profile

Concretely, this gives it access to:

• Email address of the signed-in Google Account
• The Google Account name and profile picture URL returned at sign-in (the app stores only the email)

3. How the data is used

The email is used only to tell whether the signed-in person is a registered admin, parent or child, and to attach study records to the right family member.

4. Storage and retention

• The app's own hosted Turso (libSQL) database holding families, members, answers and game statistics
• Cookies for sign-in and profile selection, and browser local storage for grade and sound preferences

5. Sharing and disclosure

The app does not sell, rent or trade Google user data, and it does not transfer it to anyone except the services listed below, which are the technical providers the app depends on.

• Google Sign-In — The sign-in request and the returned account identity.
• Google Fonts — The visitor's IP address when web fonts are loaded.
• Cloudflare — Traffic to the app, as its hosting provider.
• Turso — The stored application data, as its database provider.

No Google user data is used for advertising or re-targeting, and none of it is used to determine creditworthiness or for lending purposes.

6. Limited Use

7. Who can see the data

The person who signed in and the operator. No one else reads it; it is not made public and it is not shared with other users of the app.

8. Security

• The app runs under a Google Account with the authorizations that the owner granted.
• Credentials and API keys are kept in server-side secret storage or Google-managed storage, never in public files.
• Network requests are made over HTTPS.

9. Revoking access and deleting data

• Revoke the app's access at any time at myaccount.google.com/permissions. The app stops working immediately afterwards.
• Delete the app's data in the app itself, or in the storage listed in section 4.
• Data the app stored inside a Google Account is deleted by deleting it there; there is no separate copy held by the operator.

10. Changes to this policy

If the app's data handling changes, this page is updated and the "Last updated" date above changes with it. The current version is always this page.

11. Contact

Operated by Hidenobu Nagai. The support address for the app is set as the support address on the app's OAuth consent screen. You can also reach the operator through https://github.com/hidenobunagai.