Privacy policy

The short version

Studying works without an account, and what you study stays on your device unless you sign in. We do not sell your data, we run no advertising, and there is no analytics or tracking SDK in the app.

What we hold

With an account: your name, your email address, and a hash of your password — never the password itself. If you sign in with Apple and hide your address, we hold the relay address Apple gives us, which is all we ever see.

Your study data, once it syncs: your decks, the cards in them, and each card’s review state — how often you have seen it, how it went, when it is next due.

Your settings, so a second device matches: theme, reminders, auto-play, furigana, and the level you picked.

Your subscription status: whether premium is active, which product it came from, and when it runs to. We never see your card details.

What stays on the device

Everything, in the first place — the app is offline-first, so your decks are readable with no network at all. Signing out leaves them where they are rather than wiping them.

Your day-by-day activity log is device-only and never leaves the phone: it is not part of what syncs.

Sign-in tokens are kept in the system keychain (Keychain on iOS, Keystore on Android). In a browser they are kept in local storage, which anything running on that page can read — one reason the web build is a preview rather than the product.

Who else is involved

Apple or Google, when you sign in with them or buy a subscription. They tell us that a purchase happened and, for Apple, an address or a relay for it — nothing else about you.

RevenueCat, which records purchases and tells our server when one starts, renews, lapses or is refunded. It knows your account id with us and what you bought.

Resend, which delivers the one kind of email we send: a six-digit code when you ask to reset your password. It sees your email address and that code.

Our own server and database, hosted on Amazon Web Services. Nobody else gets a copy.

What you can do about it

Export it: Settings → Export my data writes one JSON file with your account details, decks, cards, review history, settings and activity log.

Delete it: Settings → Delete account removes your account and everything synced to it from our servers, permanently, including the subscription record. It is immediate, and we cannot undo it.

Keep it local: do not sign in, or sign out. The app keeps working.

How long we keep it

Your account data for as long as the account exists. Password-reset codes for fifteen minutes, and they can only be spent once. Purchase records for as long as we are required to keep them for accounting.

Questions

Write to support@cards-inc.com. If you want to know what we hold about you, the export above is the fastest answer; ask us and we will send it too.