Privacy Policy

Cardstock is a tool for tracking the value of your Magic: The Gathering collection. This policy explains what we collect, why, and the control you have over it. In plain terms: we only hold what we need to run the app for you, and we don't sell your data.

What we collect

• Account info — your email address, used to sign you in. Cardstock has no passwords: we email you a one-time code instead, so there is no password for us to store or for anyone to steal. Authentication is handled by Supabase.
• Your collection — the cards, quantities, cost basis, purchase dates, and watchlist entries you add or import. This is the data the app exists to track for you.
• Basic technical data — standard server logs and privacy-friendly, aggregate usage/error analytics (e.g. page views and crashes) to keep the app working. This isn't used to profile you or serve ads.

How we use it

Only to provide the service: valuing your collection, drawing your charts, computing the experimental risk signals, and keeping you signed in. We do not sell your data, share it with advertisers, or use it for anything unrelated to running Cardstock.

Where it's stored

Your data lives in a Supabase (PostgreSQL) database and the app is hosted on Vercel; both act as our processors. Card reference data (names, images, prices, legalities) comes from Scryfall and MTGJSON — that's public catalog data, not your personal information.

Cookies

We use a small number of essential cookies to keep you signed in. We don't use third-party advertising or cross-site tracking cookies.

Your rights & choices

• Export your entire collection as a CSV at any time from Settings.
• Delete your collection (cards, watchlist, and value history) while keeping your account.
• Delete your account — this immediately and permanently removes your account and all associated data.

Data retention

We keep your data for as long as your account exists. When you delete your collection or account, the corresponding data is removed from our active database.

Changes

If this policy changes materially, we'll update the date above and, where appropriate, note it in the app.

Contact

Questions about your data, or want it deleted? Send us a note through the feedback formand we'll get back to you.