Privacy policy

The short version

• No accounts, no sign-in, no ads, and nothing is ever sold or shared with data brokers.
• The app contains no analytics or tracking code. The website uses Google Analytics to count visits.
• Positions and games you analyze are sent to our engine servers so Stockfish can look at them. They are not tied to you.
• Board photos and screenshots you scan are read on the spot and not kept.
• Feedback you send is stored so we can read it and reply if you left an email.

What we process, and why

Positions and games

Game review sends the moves of the game, including any player names and headers that came with it, to our engine server at sf.chess411.com, where Stockfish evaluates every move and sends the verdicts back. The website's next move calculator and analysis board send the position on the board the same way. In the iOS app, the next move calculator runs Stockfish on your phone and sends nothing.

The engine server does not ask who you are and attaches no identifier to a request. It keeps daily counts of how many requests it served and how long they took, so we know when it needs more hardware, and it may hold a position's evaluation in a short-lived cache keyed by the position itself so a repeated position answers faster. The games themselves are not stored.

Importing games from Chess.com and Lichess

When you type a username to import games, your browser or phone asks Chess.com's or Lichess's public API for that player's recent games directly. The username is sent to them, under their own privacy policies. We do not store it.

Board photos and screenshots

The position scanner only runs when you choose to scan. On the website the image is read in your browser and never uploaded. In the app the image is sent to our server at server.chess411.com, which finds the board, reads the pieces, returns the position and discards the image; nothing is saved. The app asks for camera or photo library access only at that moment and never reads your library otherwise.

Puzzles and the daily challenge

Puzzles and the daily challenge are fetched from server.chess411.com with no identifier. Your progress, streak, lives and settings live on your device, in the app's storage or your browser's local storage. Deleting the app or clearing site data removes them; we hold no copy.

Feedback

The Send feedback form stores what you type: the category, your message, an email address if you choose to leave one, the page you were on, some technical context (the board position or puzzle, your screen size, your settings), the last few script errors from your visit, and a screenshot if you attach one. We also keep your browser's user agent and a one-way hash of your IP address, used only to stop abuse of the form. Feedback is read by the people who make Chess411, used to fix and improve it, and kept for as long as it is useful for that. Ask and we will delete yours.

The form, and the website's engine requests, are protected by Cloudflare Turnstile, a bot check that runs in your browser and sends signals to Cloudflare under Cloudflare's privacy policy.

Website analytics

chess411.com uses Google Analytics to understand which pages are read and on what kind of device. It sets cookies and sends pages viewed, approximate location and browser details to Google under Google's privacy policy. You can block it with a content blocker or Google's opt-out add-on. The iOS app has no analytics of any kind.

Hosting and server logs

The website is served by Cloudflare. Our engine and API servers run on machines we rent. Like every server on the internet, they may record the IP address, time and path of each request in short-lived logs used for security and debugging. Those logs are not used to identify you and are not combined with anything else.

What we don't do

• We never sell, rent or trade any data, and we show no advertising.
• We do not track you across other apps or websites and use no advertising identifiers.
• We do not build profiles. There is nothing to build one from.
• Chess411 is not directed at children under 13 and we do not knowingly collect personal information from anyone, of any age.

Your choices and rights

Everything the app remembers is on your device; delete the app to remove it. On the website, clear the site's data in your browser. If you live somewhere with data protection rights, such as the EU, the UK or California, you can ask to see, correct or delete anything we hold about you. In practice that means feedback you have sent. Use the Send feedback link in the footer and we will take care of it.

Changes

If what Chess411 does with data changes, this page changes with it and the date at the top moves. Nothing here will be quietly loosened.