Your collection is personal. The policy should be plain.

Information Arcanum receives

When you sign in

OpenAI Sites supplies Arcanum with a site-scoped user identifier, your email address, and, when available, a display name. Arcanum uses these details to authenticate you, label your personal library, associate records with the correct member, and administer beta admission or waitlist status. Beta records can include status, position, activation deadlines, admission timestamps, administrator role, and notification-delivery state.

When you build a library

Arcanum stores collection cards and quantities; printing details such as set and collector number; optional finish, condition, language, and recorded purchase-price fields from an import; cached marketplace estimates and their refresh time; library membership; and collection adjustments.

When you import

Arcanum keeps the source file name, import mode, time, a server-computed content fingerprint, normalized card rows, author, status, and change history so it can detect duplicates, attribute changes, and support undo. The original file is not retained as a downloadable blob, but parsed provenance can include an original per-row card label alongside its normalized identity.

When you save or improve a deck

Arcanum stores saved deck names, cards, sections, format, source recipe or library, ownership and power settings, missing-card budget, archetype and themes, combo preference, and the intent text you provide. Accepted Arcane Draft cards become ordinary deck changes; for activated members, the interface requests a save after each accepted card. Arcane Draft's pool choice, passed cards, chapter position, and undo history stay in per-tab browser storage. If you publish a deck snapshot, Arcanum also stores its visibility, public author label, primer, share slug, source version, and copied card rows. If you report a shared deck, it stores the reason and, when signed in, your site-scoped identity so repeated abuse can be investigated. Deck imports and solo playtest state used only in the browser stay on that device unless you choose a server-backed action. An Arcanum AI journey can follow Collection, Discover, Brew, and History and attach to a saved deck. It stores player messages, normalized validated assistant responses, server-issued card actions, applied-action state, a bounded rolling summary, and bounded snapshots of the active page and selected card, recipe, deck, or import.

How the information is used

• Show, search, filter, and update your collection.
• Rank deck recipes against cards in the active library.
• Build suggestions and identify missing cards.
• Provide reversible imports and an attributable audit history.
• Create and redeem limited-time invitations to shared libraries.
• Administer a limited beta cohort, waitlist, activation windows, and service-readiness controls.
• Save decks, validate deck structure, rank allowlisted additions or cuts, and—when you request it—produce Arcanum AI advice.
• Protect library access, troubleshoot the service, and prevent abuse.
• With your opt-in choice, measure first and returning visits, completed imports, and successful collection-to-recipe matches during the beta.

Optional product events use a random browser identifier. When you are signed in, the event also stores your site-scoped user ID as user_id. Visit metadata is the page path. Completed-import metadata is source (file or product), mode (append or snapshot), rows, and total cards. Successful-match metadata is recipe_id, format, and ownership_percent. These events do not include card names, your collection list, or import-file contents.

Arcanum does not sell personal information or currently run advertising. OpenAI Sites separately provides hosting, authentication, and top-level traffic analytics; Arcanum's analytics choice does not control OpenAI's platform processing.

Storage and retention

Library cards, parsed import provenance, normalized import history, beta membership records, and saved decks remain in the hosted database until you remove the applicable record or delete your Arcanum account. Unpromoted waiting or failed waitlist entries are removed after 90 days during routine beta maintenance; you can also leave the waitlist sooner. Promotion and delivery records remain until account deletion. Undoing an import reverses its collection changes but retains its audit record. Original import files are not retained as blobs.

Arcanum AI journeys retain player messages, page-context snapshots, and normalized, schema-validated assistant responses—not raw OpenAI request or response bodies. A journey follows navigation and, once attached, belongs to one saved deck; saved-deck journeys never mix. It holds at most 40 messages and expires 30 days after its latest activity. Starting over deletes that journey immediately; deleting the saved deck cascades to it; account export includes the journey and messages; and account deletion removes them. Separate AI run rows retain user-linked operational metadata such as request and deck references, status, model and prompt/scorer versions, token counts, estimated cost, outcome code, latency, feedback, and timestamps for 30 days. Anonymous monthly spend totals use a 13-month accounting window. OpenAI's separate API retention is described above.

Product events older than 90 days are excluded from beta metric views. A later opted-in analytics event purges event rows older than 90 days; if no later event arrives, stale rows may remain until that purge runs. Linked rows are also removed when a signed-in user deletes their Arcanum account.

If you opt in, Arcanum sets a first-party, HttpOnly random-visitor cookie after the first accepted event. Each later accepted event renews it, so it can remain for up to one year after the most recent event unless you remove site data sooner in your browser. Declining analytics sends no Arcanum product event and sets no analytics cookie. Short-lived abuse-prevention counters expire with their rate-limit window.

Your analytics choice is stored only in your browser's local storage until you change it, delete your Arcanum account, or clear site data. Your light or dark appearance choice is also stored locally on the device and is not sent to Arcanum; when no choice is stored, the interface follows the browser or operating-system color-scheme preference. Clearing site data removes the saved appearance choice. Guest Brew stores the selected format, deck list, commander, and starting recipe in per-tab session storage so the brew survives a refresh; Arcanum does not receive that guest Brew state. Browsers normally clear it when the tab's page session ends, and Arcanum also clears it in that browser after a successful account deletion.

For an activated member, Brew also keeps the current working draft in per-tab session storage so an unsaved edit can survive a refresh. That device-local record can include the deck name, cards, quantities and sections, format, commander, source recipe, saved-deck reference and version, ownership and power settings, missing-card allowance, combo preference, archetype, themes, and intent text. It is namespaced to your site-scoped identity, is not synced between devices, is not included in account export, and is sent to Arcanum only when you choose a server-backed action such as Save, Analyze, or Arcanum AI. Closing the tab's page session or clearing site data removes it; signing out alone may not. Account deletion clears it on the browser performing the deletion, while other devices must be cleared separately.

Arcane Binder can remember the selected view and shelf plus a shortlist in local storage, and the last selected card, chapter position, and cards explored in per-tab session storage. This bounded state contains card identifiers and interface settings—not card images, Oracle text, or a copy of your collection—and is namespaced to the signed-in identity and active library on that browser. It is device-local, is not synced, is not included in account export, and does not reach Arcanum's server unless you choose a separate server-backed action such as changing collection quantity or adding a card to a Brew. Use “Clear browsing state” in Arcane Binder to remove it for the active library. Account deletion clears all Arcane Binder state on the browser performing the deletion; other devices must be cleared separately. Signing out does not clear it, so clear browsing state or browser site data before leaving a shared device.

Arcane Draft stores up to 500 recent add/pass decisions, its current card-pool choice, and chapter position in per-tab session storage under the active identity and library or Guest Brew namespace. This lets the ritual survive a refresh and supports undo without sending passed-card choices to an account. Accepted cards are sent only through the ordinary saved-deck action for activated members; Guest Brew remains local. Closing the page session or clearing site data removes the device history.

After an account deletion, Arcanum keeps a one-way hashed marker derived from the site-scoped user ID for up to 24 hours. It is used only to keep overlapping requests from recreating account data while deletion finishes; after that period, the marker is ignored and removed during later cleanup.

Reasonable technical and access controls are used, but no internet service can promise absolute security. Keep shared-library invitation links private and use a trusted device for imports.

Your choices

• Browse public deck recipes without signing in.
• Use Guest Brew without signing in; its temporary deck state stays in that browser tab.
• Save an activated member's working Brew to the account, or remove its unsaved per-tab copy by closing that page session or clearing browser site data.
• Use Arcane Binder's “Clear browsing state” control to remove the active library's local shortlist, view, and resume state from that browser.
• Join or leave the beta waitlist from the access-status card, when waitlisting is available.
• Save and delete individual decks; keep them private or publish a versioned unlisted/public snapshot and remove it later. Arcanum AI is optional; do not submit a goal if you do not want that deck and bounded conversation context sent to the OpenAI API. Start over clears one deck's conversation without resetting its usage allowance.
• Allow, decline, or revisit optional analytics at any time. Switching from allowed to declined stops future Arcanum product events, asks Arcanum to delete events linked to that browser identifier, and expires its analytics cookie. If that request fails, the site tells you so and you can retry; browser site-data controls can also remove the cookie.
• Disable Scryfall metadata resolution before an import.
• Adjust quantities, undo eligible imports, or archive a shared view you own.
• Download a JSON export of your account, personal libraries, cards, normalized import history, saved decks, and Arcanum AI conversations from Library controls.
• Delete your Arcanum account and personal collection data from Manage account and library. This control remains available when beta access is expired or revoked. For an ordinary tester this also purges beta and waitlist records, saved decks, and user-linked coach metadata, and releases the tester seat. Shared references needed for integrity are anonymized, and shared views you own are archived.
• Sign out to end your current session. Signing out does not delete stored library records.

If you are the sole beta administrator, account deletion is blocked with an administrator-transfer requirement until the role is transferred. This avoids silently retaining your identity or leaving the beta without an operator. Operator actions are written to an append-only audit using random audit references rather than site-scoped identity IDs. Account deletion removes the private mapping for that person, leaving the retained audit reference anonymous without rewriting the audit event. Some information may also be retained where required for security, integrity, dispute resolution, or legal compliance. OpenAI account and ChatGPT data requests must be made to OpenAI directly.