Open Source Licences

Browser-distributed components

Components distributed to your browser

GPL-licensed components distributed to end users require us to publish attribution and source code links. The following components are bundled and delivered to your browser as part of the ChessSmith service.

Stockfish GPL v3

Chess engine — distributed to your browser as a WebAssembly binary (Pro feature)

Authors: The Stockfish developers. Originally by Tord Romstad, Marco Costalba, Joona Kiiski, and Gary Linscott.
Source code: github.com/official-stockfish/Stockfish
Licence: GNU General Public License v3.0
How used: A Stockfish WebAssembly binary is loaded in your browser when you use engine analysis (Pro). The WASM binary analyses positions locally — no position data is sent to external Stockfish servers.

GPL v3 obligation: Because Stockfish is distributed to end users as a WebAssembly binary, GPL v3 requires attribution and a link to the source code. Both are provided above.

Chessground GPL v3

Interactive chessboard library — distributed to your browser

Authors: Lichess.org and contributors
Source code: github.com/lichess-org/chessground
Licence: GNU General Public License v3.0
How used: Chessground renders the interactive chessboard in the repertoire builder, training interface, and game review UI. It handles piece movement, board highlighting, arrow drawing, and position display.

GPL v3 obligation: ChessSmith's frontend source code is available on request at support@chesssmith.com in accordance with GPL v3 obligations. A source code link will be published here when the frontend repository is made publicly available.

Merida Chess Pieces GPL v2

Chess piece SVG graphics — distributed to your browser via the Chessground library

Authors: Armando Hernandez Marroquin (original Merida TrueType font). Adapted as SVG graphics for Chessground by the Lichess team.
Source code: github.com/lichess-org/lila
Licence: GNU General Public License v2.0
How used: The Merida chess piece SVG graphics are displayed on the interactive chessboard throughout ChessSmith — in the repertoire builder, the training interface, and the game review UI.

chess.js MIT

Chess move validation and game logic library — distributed to your browser

Authors: Jeff Hlywa and contributors
Source code: github.com/jhlywa/chess.js
Licence: MIT License — unrestricted commercial use permitted, no copyleft obligations
How used: chess.js validates legal moves, generates FEN strings, parses PGN notation, and handles chess game logic in the browser. Used throughout the repertoire builder and training interface.

Server-side only

Server-side components

The following components are used only on ChessSmith's servers and are never distributed to your browser. The GPL SaaS exception applies — no client-side disclosure is required. Attribution is included here as a courtesy.

python-chess Server-side only GPL v3

Chess logic library — server-side only, not distributed to browsers

Authors: Niklas Fiekas and contributors
Source code: github.com/niklasf/python-chess
Licence: GNU General Public License v3.0
How used: Used exclusively on ChessSmith's backend to validate moves, generate FEN strings, parse PGN files during game import, and identify checkmate and stalemate positions.

ECO Opening Classification Data Server-side only MIT

Encyclopaedia of Chess Openings codes and names

Authors: Lichess.org and contributors
Source code: github.com/lichess-org/chess-openings
Licence: MIT License — unrestricted commercial use, no attribution required. Attribution included here as a courtesy.
How used: Labels positions with their standard opening name (e.g., "Sicilian Defence, Najdorf Variation") in the repertoire builder and training UI. Stored as a seed table in ChessSmith's database and looked up server-side.

DMCA designated agent

ChessSmith hosts user-generated content in the form of publicly shared opening repertoires, including move annotations. We respect the intellectual property rights of third parties and will respond to valid copyright notices under the DMCA and its international equivalents.

Designated agent

To report copyright infringement in a shared ChessSmith repertoire, send a written notice to: support@chesssmith.com

What a valid notice must include

Your name, postal address, email address, and telephone number
A description of the copyrighted work you claim has been infringed
The URL of the ChessSmith shared repertoire containing the allegedly infringing material
A statement that you have a good-faith belief that the use is not authorised by the copyright owner, its agent, or the law
A statement, made under penalty of perjury, that the information in the notice is accurate and that you are the copyright owner or authorised to act on their behalf
Your physical or electronic signature

Note on chess moves: Chess moves and opening sequences are facts and are not subject to copyright under Australian law, US law, or the Berne Convention. Only original written commentary and annotations may be copyrightable. Notices that target only move sequences will not be acted upon.

Counter-notices

If content you published was removed and you believe the removal was in error, you may send a counter-notice to the same address. A valid counter-notice must include your name, address, and contact details; identification of the removed content; a statement under penalty of perjury that you have a good-faith belief the material was removed by mistake; your consent to the jurisdiction of the courts in Victoria, Australia; and your physical or electronic signature.

Repeat infringer policy

ChessSmith will terminate the accounts of users who receive two or more valid, uncontested DMCA takedown notices relating to content they have published.

EU compliance

EU Digital Services Act (DSA)

ChessSmith hosts publicly shared user content and therefore operates as a hosting service under the EU Digital Services Act for users in the EU and EEA.

Reporting illegal content

EU users who encounter content in a shared ChessSmith repertoire that they believe is illegal may report it by emailing support@chesssmith.com with a description of the content, its URL, and the specific law they believe it violates. ChessSmith will assess all reports without undue delay and notify the reporter of the outcome.

Point of contact for DSA matters

Email: support@chesssmith.com

ChessSmith's current user base does not reach the "very large online platform" (VLOP) threshold under the DSA (45 million EU monthly active users). The obligations described on this page reflect those applicable to standard hosting services.

Trademarks

Third-party trademarks

ChessSmith integrates with Lichess (lichess.org) and Chess.com. References to these services are for descriptive purposes only — to explain which platforms ChessSmith can import game data from. ChessSmith is not affiliated with, endorsed by, or sponsored by Lichess, Chess.com, FIDE, or any other chess organisation or platform.

Lichess and Chess.com are trademarks of their respective owners. Their names are used here under nominative fair use only. ChessSmith does not use the logos or branded assets of any third-party platform.

ECO opening names (e.g., "Sicilian Najdorf", "London System", "Queen's Gambit Declined") are not trademarked. They are standard descriptive terms in common use throughout the chess world.

Process

Dependency audit process

ChessSmith runs automated licence audits before each release. Backend Python dependencies are audited using pip-licenses. Frontend npm dependencies are audited using license-checker. Any GPL or AGPL packages that are distributed to user browsers are assessed for copyleft obligations and added to this page.

This page is updated whenever a new component is added or an existing component's licence terms change. If you identify a missing attribution or a licence compliance concern, please contact support@chesssmith.com.