Privacy

Privacy policy

Last updated: 2 October 2026

PolyMind Chess is published by Cyril Dieumegard. The principle is simple: as much as possible runs in your browser, and the server keeps only what is needed for your account and subscription.

Data stored in your browser

Your game history, player profile, coach Léon’s memory and preferences are stored on your device. Stockfish, speech synthesis and transcription run locally where the browser supports them. Private multiplayer games are the exception described below.

Private multiplayer games

When you play with a friend, Cloudflare temporarily stores the room code, each player's account identifier and display name, the moves, position and result so both devices stay in sync. Waiting rooms expire after 30 minutes; started games expire after 24 hours and their shared data is deleted. Your opponent sees your display name, not your email address. Finished games can be saved locally or exported by either player. No voice recording or coach memory is shared with your opponent.

Account data

Sign-in uses Google. We receive only your Google identifier, email address, name and profile photo. We also store your plan (free or paid) and the number of games used. This information is stored in a Cloudflare D1 database.

Payment

Payments are processed by Stripe. We never see or store your card number; we keep only the Stripe customer and subscription identifiers.

Decision engines

When you play against a JEV opponent, the position and short questions about the game are sent to the TypeSafe API through our relay. No identity data is attached to these requests.

Analytics

We use DataFast to measure visits and anonymous events (such as starting a game or opening checkout). No advertising is displayed and your data is never sold.

We also measure automated crawler requests to public pages. DataFast receives the page URL without query parameters, the crawler’s user agent, its Cloudflare-provided IP address for verification, and the HTTP response status. This server-side tracker does not send cookies, authentication headers, referrers, account data or game content. API requests are excluded.

Your rights

• You can erase local data at any time by clearing this site’s data in your browser.
• You can request access to, correction of or deletion of your account by writing to [email protected]. Deletion is completed within 30 days.
• You can revoke PolyMind Chess’s access to your Google account in your Google account permissions.

Use of Google data

Our use of information received from Google APIs complies with the Google API Services User Data Policy, including the Limited Use requirements. This information is used only to identify you in PolyMind Chess.

Contact

For any questions: [email protected].