Privacy Policy

Liu Cards · Last updated: July 20, 2026

Liu Cards is a flashcards and spaced-repetition app made by Codesuma ("we", "us"). This policy explains what information the app handles, how it is used, and the choices you have. We keep the app simple, and we keep this policy simple too.

The short version

• No account or email is required to use the app.
• We only handle the cards you create and the study data needed to schedule your reviews.
• Cards you publish to a channel are visible to other users — everything else is private.
• We do not show ads, and we do not sell your data.
• We do not collect your location, your contacts, or advertising identifiers.

Information we handle

Anonymous identity. When you first save something, the app creates an anonymous account for you on our backend (a random user ID and a security token), along with a random device identifier. This lets your cards be stored and, once you sign in, follow you across devices. It does not require your name, email, or phone number.

Your content. The flashcards you create — the text on their front and back — are stored on our servers so they can be saved and synced.

Study data. To schedule reviews, we store which cards you saved and how you rated each review (for example "Hard" or "Good"), together with timing data the scheduling algorithm needs.

Channel content. Channels are public collections. If you create a channel and publish cards to it, the channel's name and those cards are visible to other users, and other users can save them into their own decks. We also store which channels you subscribe to.

Optional sign-in. If you choose to sign in with Google or Apple to secure your account, we receive your email address from that provider to link your account. This is optional — the app works fully without it.

What we do not collect

• Precise or approximate location.
• Your contacts or address book.
• Advertising identifiers — the app contains no ads and no advertising SDKs.

How we use information

• To provide the app: saving your cards and scheduling your reviews.
• To enable channels: showing cards you publish to the users who browse or subscribe to your channel.
• To keep the service working and secure (for example, preventing abuse).

We do not use your information for advertising or profiling, and we do not sell it.

Who we share it with

We share your information only as needed to run the app:

• Other users. Only the cards you publish to a channel, and the channel's name, are visible to others. Your private cards and study data are not.
• Infrastructure providers. We use Supabase (database and authentication) and Fly.io (hosting) to operate the service on our behalf. Your data is processed on their infrastructure under their security measures.
• Legal reasons. If required by law or to protect rights, safety, and the integrity of the service.

Data security

Data is encrypted in transit (HTTPS) between the app and our servers. Your account is protected by a security token rather than a password you have to manage.

Data retention and your choices

You can delete individual cards at any time inside the app, which removes them from our servers. To delete your account and all associated data, see liucards.app/delete or email us at info@codesuma.dev and we will process your request.

Children

Liu Cards is not directed to children and is intended for a general audience. We do not knowingly collect personal information from children. If you believe a child has provided us information, contact us and we will remove it.

International processing

Our service providers may store and process data on servers located in other countries. By using the app, you understand your information may be processed in those locations.

Changes to this policy

We may update this policy from time to time. We will revise the "Last updated" date above when we do, and significant changes will be reflected on this page.

Contact

Questions about this policy or your data? Email us at info@codesuma.dev.