Local progress
Progress, bookmarks, notes, drawings and review attempts are saved using browser local storage. Downloaded lessons use browser Cache Storage. The application has no account system, advertising trackers or analytics scripts. Your browser requests static pages and assets from the hosting provider, which may keep operational access logs according to its own policies.
Export study data from My study to keep a copy. Importing a study file replaces the current local record. Clearing browser site data removes local progress and offline downloads. Removing an offline lesson inside the app leaves your study record intact.
Sharing and installation
Sharing occurs only after you choose an action. WhatsApp, X and email links pass the selected public lesson URL to the chosen service. No notes or review data are included. Native sharing is handled by your device. Downloaded position images are generated in your browser.
Installing the app does not automatically save the game archive. Use Save for offline on a lesson and wait for a complete-download confirmation. Browsers may evict cached assets when storage is low.
Open-source software and artwork
The interactive board uses @chesshere/chessboard 0.1.0, pinned to commit 2d46c2046f46995131ec46a9dc49e64b548b3ab2, under the MIT licence. Chess rules use chess.js (BSD-2-Clause). The website uses Astro (MIT).
Classic pieces: Colin M. L. Burnett and Wikimedia contributors, distributed under the BSD-3-Clause licence. Celtic pieces: Maurizio Monge, under the MIT licence. Read the bundled artwork notices. No noncommercial or unlicensed piece artwork is used.
Analysis is produced with Stockfish 17.1, GPLv3. The engine binary is not shipped to browsers. Its exact identity and analysis configuration are saved with every game. Self-hosted DM Sans and Newsreader fonts are distributed under the SIL Open Font License; licence files are included in the source dependencies.
Content and historical data
Game pages link to their factual game-score sources. Source annotations are excluded. Original educational explanations are AI-assisted; see our editorial method. Game scores are records of moves. We do not claim rights over those underlying facts.