Draft: this page is still being reviewed and may change.
Last updated 6 October 2026
OPTCG Deck Planner (optcg-deck-planner.app) and OPTCG Duel (optcgduel.app) use a small number of cookies, all needed for signing in. We do not use advertising or tracking cookies, and our analytics do not use cookies, so there is nothing to opt into.
Cookies we set
| Name | Purpose | Lasts |
|---|---|---|
optcg_session | Keeps you signed in. Not readable by page scripts. | 30 days, or until you log out |
optcg_oauth_nonce | Protects the Google sign-in step from forgery. | 10 minutes |
optcg_oauth_return | Remembers which app to return you to after Google sign-in. | 10 minutes |
Google sets its own cookies on its sign-in pages. Those are covered by Google’s privacy policy.
Storage in your browser
The apps also save things in your browser’s local storage, session storage and IndexedDB. These stay on your device and are not sent to us unless the feature says so (for example, settings sync when you are signed in).
- Preferences such as theme, list or grid layout, sorting, filters and open panels.
- OPTCG Duel settings, saved decks, and the selected deck.
- Your playmat and card back images, cached so matches load quickly.
- A guest ID if you play without signing in.
- A cache of card data used by the card scanner.
- Short-lived notes such as the match to rejoin after a reload and the page to return to after signing in.
Clearing them
You can delete cookies and site data in your browser settings at any time. Clearing the session cookie signs you out, and clearing site data resets your device preferences and any decks you saved only on that device.