Copyright & Attributions

We are deeply grateful to Thibault Duplessis, the Lichess team, and the entire open-source chess community for building world-class free chess infrastructure and making chess education freely accessible to learners worldwide.

Tactical puzzles, training lesson drills, and master position game datasets across ABCChess are sourced from the public Lichess Open Database (database.lichess.org), released under the Creative Commons CC0 1.0 Universal Public Domain Dedication and Open Database terms.

Chess move, capture, check, castle, promotion, and countdown audio effects across ABCChess are adapted from the open-source Lichess project (lila), distributed under the GNU Affero General Public License v3 (AGPLv3).

Computer sparring, in-browser move evaluation, and post-game game reports are powered by Stockfish.js (WebAssembly), based on the world-leading open-source Stockfish chess engine.

Stockfish is developed by Marco Costalba, Joona Kiiski, Gary Linscott, Tord Romstad, Stéphane Nicolet, and the Stockfish open-source contributors, licensed under the GNU General Public License v3 (GPLv3).

Client-side chess move generation, check/checkmate verification, FEN position parsing, and PGN export are built using chess.js, created by Jeff Hlywa and open-source contributors under the BSD 2-Clause License.

Icons: Clean user interface iconography is provided by Lucide Icons under the ISC License.

Typography: Platform typography uses the Nunito font family, created by Vernon Adams, Cyreal, and Jacques Le Bailly, licensed under the SIL Open Font License (OFL 1.1).

Avatars: Computer personality avatars are generated via DiceBear under CC0 1.0 Universal public domain.

© 2026 ABCChess LLP. All rights reserved.

All proprietary coaching curriculums, lesson drills, training modules, design system tokens, and platform software remain the exclusive property of ABCChess LLP.

For licensing inquiries or questions regarding third-party credits, please reach out to legal@abcchess.org.