The short version

Atsumia keeps your collection, your pack history and your display name on its server. An account adds your email address. Interface preferences stay in this browser.

In detail

On the server: your display name, the language and time zone your browser reported, every card you own, and every pack you have opened. With an account, your email address, and a hash of your password if you set one.
Every sign-in writes a session row carrying the IP address and browser user agent it came from. Logging out revokes that row; logging out everywhere revokes all of them.
A sign-in code is stored as a hash rather than as the code, next to the IP address that asked for it, and expires after ten minutes.
None of this is on a retention timer. The address stays until you delete the account; the collection and the pack history stay, because ownership is what the game is.
Sign-in codes are delivered by Brevo, which receives your address in order to send the mail. The message is plain text, with no images and no tracking.
The sign-up and sign-in forms run Cloudflare Turnstile. Checking it sends the widget’s token and your IP address to Cloudflare.
Card images are fetched from Wikipedia and Wikimedia Commons, which means those requests reach Wikimedia.
The database is dumped nightly and the dumps are kept for 30 days. An address you delete can therefore survive in a backup for up to 30 days after it has gone from the live database.
Deleting your account, from Settings, is a tombstone: your email address, its verification, your password and your display name are erased, every sign-in code for the address is deleted, and every session is revoked. Your collection and your pack history stay, on a row that no longer says who you were. It requires a fresh sign-in code and cannot be undone.
Two things deletion does not reach: the IP address and user agent on past session rows, and the IP address on the audit rows that record privileged actions. Both remain as an operational record, and neither carries your address once it is erased.
In this browser: your interface preferences, and the keys that let a pack open be retried without opening two. You can export that as JSON from Settings and erase it from the same screen. Neither touches your collection on the server.
No location permission is requested. Local packs and travel features would require explicit opt-in before ever being built.

Your choices

Settings control motion, text size, sensitive imagery and your local data, with no hidden flow.

Manage settings