Your email address, a hashed (never plain-text) password, an optional display name and birthdate (used only to confirm you meet the minimum age requirement), and whatever decks/collection entries you create.
Solely to run the app for you: keeping you signed in, saving your decks/collection, and sending account-related email (verification, and if you ask for it, a password reset). Nothing is sold, and nothing is shared with advertisers.
Card lookups are served from a local cache built from Scryfall's public data; combo lookups similarly from Commander Spellbook's public data; tournament results from TopDeck.gg, under their own API Terms of Service. Outbound email is sent through Resend. If you subscribe to a paid tier, payment is handled entirely by Polar — we never see or store your card details.
One session cookie keeps you logged in. It's not used for tracking or advertising.
You can delete your account and everything tied to it any time from your account page — it's immediate and permanent. If you run into trouble, reach us through the contact page.