Privacy Policy

Information We Collect

When you create an account, we collect your email address and password (encrypted). During use, we collect puzzle attempt data (solutions, times, accuracy) to power the spaced repetition system. We do not collect personal information beyond what is necessary for the service. Opening an analysis link containing PGN (?pgn=) sends the game to the server and CDN as part of the URL; it may appear in browser history or request logs. Directly pasted PGN is not uploaded for engine analysis. Loading a Lichess game URL or games by a Chess.com or Lichess username sends a request directly from your browser to that service, including the game identifier or username and your IP address.

If you are signed in, the following is stored with your account: puzzle attempts (whether you solved it, time taken, moves played, a review score, and a copy of the result we returned so a resent answer is not counted twice); each tactic's level, XP, review schedule and practice statistics (attempt and solve counts, streaks, average time); profile settings (onboarding status, the starting level you chose, language, plan, and if you subscribe the payment provider's customer ID, subscription ID and subscription end date); daily usage counts; bookmarked puzzles; CCT scan (checks and captures) results; loose piece drill results (the squares you picked, how many you found, missed or picked wrongly, the score and the time taken); and coaching progress from the multi-game diagnosis (the tactic, the cause you picked, the review schedule, your chess.com or Lichess username, which practice puzzles you solved, earlier rounds kept when you restart, and up to two example positions per tactic with the game link, the position, the side and move number, the move you played and the engine's best move). Positions the diagnosis excludes are not recorded. Some data stays only in this browser, signed in or not: training levels and recent puzzles while signed out, diagnosis reports and the game notation downloaded for them, the last chess.com or Lichess username you entered, a copy of coaching progress (and, while signed in, changes not yet sent to your account), engine depth settings, the waiting-screen game level, and dismissed hints. Clearing this site's data in your browser removes them.

How We Use Your Information

Your data is used to: provide personalized tactical training via SM-2 spaced repetition, track your progress across 53 tactical concepts, display your skill radar chart, and improve the service. We do not sell your personal data to third parties.

Cookies, Advertising and Analytics

We use essential cookies for authentication and session management. We also use Google Analytics to collect anonymous usage data (page views, navigation paths, and completion of the waiting-screen game with its level) to improve the service. You can block analytics collection via the Google Analytics opt-out browser add-on (tools.google.com/dlpage/gaoptout). Signed-out training levels and recent puzzle IDs are stored locally and sent in a functional preference cookie (cms_training_v1, 30 days) so the first puzzle can use them. This cookie contains no account information or game notation.

Advertising on this site uses cookies, web beacons and similar identifiers, which may record information such as your IP address, device and browser type, and the pages you visit. Third-party vendors, including Google, may place and read these cookies on your device, and use them to serve ads based on your prior visits to this website or other websites. Google's use of advertising cookies - including the DoubleClick DART cookie - enables Google and its partners to serve ads to you based on your visits to this site and other sites on the Internet. You may opt out of personalized advertising by visiting Google Ad Settings (adssettings.google.com), or opt out of a third-party vendor's use of cookies for personalized advertising by visiting aboutads.info. If you are located in the European Economic Area (EEA), the United Kingdom, or another jurisdiction with consent-based advertising requirements, you can manage your advertising preferences for Google ads through Google Ad Settings, which honors regional consent requirements.

Data Storage and Security

Your data is stored securely on Supabase (PostgreSQL) with row-level security policies. Passwords are hashed and never stored in plain text. All data transmission uses HTTPS encryption.

Third-Party Services

We use the following third-party services: Supabase (authentication and database), Google AdSense (advertising), Google Analytics (usage analytics), Cloudflare Workers (hosting), the Lichess and Chess.com public APIs (your browser requests games from them directly when you load a game link or a username), and Stockfish (chess analysis, runs locally in your browser via WebAssembly).

Your Rights

We keep this data while your account exists; we do not set a separate retention period. You may request deletion of your account and all associated data at any time by contacting us. Deleting the account removes every record linked to it listed above (puzzle attempts, skill data, profile, usage counts, bookmarks, CCT scan results, loose piece drill results and coaching progress, including earlier rounds). Coaching progress, including earlier rounds, can also be deleted on its own from the coaching panel of the multi-game diagnosis.

Contact

For privacy-related inquiries, please contact us at support@chessmotifstats.com.