Privacy Policy

Arcanum (the "Service") is an AI-powered Magic: The Gathering deck analysis tool operated by the team behind arcanum.app. We are not affiliated with Wizards of the Coast.

• Account info: email address and a name you choose. Passwords are stored hashed (never in plaintext).
• Decks you save: card lists, names, and any analysis outputs. Public decks (`/popular`) are visible to everyone.
• Usage telemetry: anonymous page views, button clicks, and feature usage via PostHog so we can improve the product.
• Billing data: if you upgrade to Pro, payment is processed by Stripe. We never see or store full card numbers — only the Stripe customer ID, transaction status, and amount.
• Logs: standard server logs (IP, user-agent, request path) for security and debugging — retained 30 days.

• To run the deck analyzer and AI features you request.
• To send you email you've explicitly opted into (verification, password resets, optional product updates).
• To prevent abuse (rate-limit spammy IPs, throttle the LLM endpoints from automated scraping).
• To maintain the public deck feed (if you mark a deck public).

We do not sell your data, and we do not run third-party advertising on Arcanum.

When you click "Buy on TCGplayer", "Card Kingdom", or "Cardmarket", you'll land on the vendor's site through a referral URL. If you make a purchase, Arcanum may earn a small commission (typically 5–10%) at no extra cost to you. This commission helps keep the free tier free. We never recommend cards based on commission rate — recommendations are generated by the LLM solely from your deck context.

We set a single cookie (or local-storage token) to keep you logged in. Analytics use first-party cookies via PostHog. You can opt out of analytics in your browser at any time — no feature is gated on tracking.

• Stripe processes payments. Their privacy policy applies to billing data they handle.
• Resend sends our transactional emails (verification, password reset).
• OpenAI (via Emergent) processes deck analysis prompts. Decks you submit are sent to OpenAI for analysis. Per OpenAI's policy, API content is not used to train models.
• Scryfall serves card data and pricing (public data, no PII shared).
• Sentry collects crash reports if you encounter an error (no decklists, only stack traces).

You can view, edit, or delete any deck you've saved at any time. You can delete your account by emailing support@arcanum.app — we'll purge your data within 7 days. EU/UK/California residents have additional rights (access, rectification, erasure, portability, objection); we honor all of them. Email the same address to invoke them.

Arcanum is not directed at children under 13. If you believe we've collected data from a minor, contact us and we'll remove it.

We'll update this page with a new "Last updated" date when we change anything material, and email logged-in users about significant changes.

support@arcanum.app