Copying Disco Chess

Any file in this project that does not state otherwise and is not listed as an exception below is part of Disco Chess and copyright (c) 2025-2026 the Disco Chess authors.

Disco Chess is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

Disco Chess is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

See the LICENSE file for a copy of the GNU General Public License.

Why GPL

The choice is not entirely ours. The app links chessground (GPL-3.0-or-later) and ships a Stockfish build (GPL-3.0). Either alone forces a GPL-family licence on the combined work, and we licence the project GPL-3.0-or-later.

The bundled board textures come from lichess-org/lila and are AGPL-3.0-or-later. They keep that licence, and it travels with them: the rows below say so, and the full text ships alongside the other licence texts. GPLv3 section 13 expressly permits combining a GPLv3 work with AGPLv3 material, which is what makes that lawful. The Stockfish and chessground combination needs no special clause: they are GPLv3-family works combined under the licence's own terms.

Exceptions (free)

Files	Author(s)	License
public/chess-assets/boards/*	the lila authors and pirouetti	AGPLv3+
public/stockfish/*	the Stockfish developers, WASM build (c) 2025 Chess.com, LLC via nmrugg/stockfish.js, NNUE nets by Linmiao Xu	GPLv3
Vendored cm-chessboard stylesheets under public/chess-assets/ (chessboard.css/.scss, _chessboard-theme.scss, extensions/)	Stefan Haack	MIT
Project scaffolding remnants (e.g. config/site.ts)	Next UI, (c) 2023 Next UI	MIT
public/chess-assets/pieces/cburnett	Colin M.L. Burnett	GPLv2+
public/chess-assets/pieces/celtic	Maurizio Monge	MIT
public/chess-assets/pieces/chessnut	Alexis Luengas	Apache 2.0
public/chess-assets/pieces/fantasy	Maurizio Monge	MIT
public/chess-assets/pieces/firi	James Faure	CC BY 4.0
public/chess-assets/pieces/kiwen-suwi	neverRare	CC BY 4.0
public/chess-assets/pieces/kosal	Kosal Sen / Philatype	CC BY 4.0
public/chess-assets/pieces/merida	Armando Hernandez Marroquin	GPLv2+
public/chess-assets/pieces/mono	Thibault Duplessis and Colin M.L. Burnett	GPLv2+
public/chess-assets/pieces/mpchess	Maxime Chupin	GPLv3+
public/chess-assets/pieces/rhosgfx	RhosGFX	CC0 1.0
public/chess-assets/pieces/shapes	flugsio	CC BY-SA 4.0
public/chess-assets/pieces/spatial	Maurizio Monge	MIT
The Nunito typeface, self-hosted at build time via next/font	The Nunito Project Authors	SIL OFL 1.1
Chess.com glyph path in components/icons/platform-marks.tsx	simple-icons	CC0 1.0
UI icons rendered through @iconify/react	Solar Icons by 480 Design (CC BY 4.0), Lucide (ISC), simple-icons (CC0), Material Design Icons (Apache 2.0), Tabler (MIT), Google Material Icons (Apache 2.0), Noto Emoji (Apache 2.0), Flat Color Icons (MIT), Font Awesome 6 Solid (CC BY 4.0), Fontisto (MIT), Heroicons (MIT), SVG Spinners (MIT), SVG Logos (CC0)	per set, as listed

The piece sets above were sourced from lichess-org/lila, which republishes them with the per-set attribution recorded in its own COPYING.md.

The Disco Chess logo and mascot artwork (public/mascots/*, the app icons and splash screens), the app-tour screenshots (public/img/app-screens/*), and the blog and marketing imagery we produced ourselves are our own work and are covered by the project licence, except where the Trademarks section says otherwise.

Trademarks (not covered by the project licence)

The marks below identify third-party products and services that Disco Chess integrates with or writes about. They are used nominatively, only to say which product something belongs to. They are not licensed under the GPL, and the project licence grants you no rights in them. If you fork this project, you are responsible for your own use of these marks.

Mark	Owner	Basis for our use
Chess.com pawn, in components/icons/platform-marks.tsx	Chess.com, LLC	Nominative use to identify the Chess.com account-linking integration. The path itself is the CC0 rendering from simple-icons, not a Chess.com file
"Download on the App Store" badge, public/store-badges/app-store.svg	Apple Inc.	Used to link to our App Store listing per Apple's marketing guidelines
"Get it on Google Play" badge, public/store-badges/google-play.svg	Google LLC	Used to link to our Google Play listing per Google's brand guidelines
Google and Apple logos in the sign-in buttons	Google LLC / Apple Inc.	Rendered per each company's sign-in branding guidelines
"The Woodpecker Method"	licensed by Chess.com, LLC and Quality Chess UK LTD	Named nominatively; the marketing pages that discuss it carry an explicit non-affiliation disclaimer
YouTube logo, rendered via the logos icon set	Google LLC	Nominative use to mark links to instructional videos hosted on YouTube
Third-party product screenshots and names in public/img/blog/* and the blog articles (Chessable, ChessTempo, ChessBase, Lichess, Chess.com, and others)	their respective owners	Nominative use in editorial product comparisons; the screenshots depict the products under discussion

"Disco Chess", the Disco Chess logo, and the mascot are trademarks of the Disco Chess authors. The GPL gives you the right to fork the code; it does not give you the right to ship your fork under our name or marks.

Removed assets

These previously shipped and were removed during the licence audit. They must not be restored:

• public/fonts/GothamRounded/*: Gotham Rounded is a commercial typeface licensed from Hoefler&Co for our own use only. It cannot be redistributed in a source repository. Replaced by Nunito (OFL).
• public/chess-assets/pieces/shahi-ivory-brown: the SAHI set is explicitly no-derivatives, which conflicts with GPL section 7's prohibition on further restrictions. Removed rather than carried as a special case.
• public/img/chesscom-pawn.webp: a Chess.com image file of unclear provenance. Replaced by the CC0 simple-icons rendering in components/icons/platform-marks.tsx.
• public/chess-assets/boards/ncf-board.png, public/next.svg, public/vercel.svg: orphaned files with no references.
• public/img/blog/author-mike-reynolds.webp: an AI-generated portrait for a bylined author persona; removed as unused.

Redrawing any removed asset with small changes would still produce a derivative work and would not fix the problem.

Source for the binaries

The GPL requires that anyone who receives a Disco Chess binary can get the corresponding source. The web app at discochess.com and the iOS and Android apps are built from this repository; the published source corresponds to what is deployed. The bundled Stockfish build corresponds to nmrugg/stockfish.js at the version recorded in the banner comment of public/stockfish/stockfish-17.1-lite-51f59da.js, which in turn corresponds to official-stockfish/Stockfish. The dependency patches under patches/ are part of the corresponding source: the patched packages are not distributed unmodified.

External services

Disco Chess talks to these services. They are not part of this work and are not covered by its licence:

• api.discochess.com for accounts, puzzles, and progress
• Firebase Authentication for sign-in
• Mixpanel and Google Analytics for product analytics
• RevenueCat for mobile subscriptions, Stripe for web payments
• Applixir for rewarded ads (web only)
• the Reddit advertising pixel for ad conversion measurement (web only)
• YouTube (privacy-enhanced youtube-nocookie.com embeds and thumbnails) for instructional videos
• api.iconify.design for UI icon data
• lichess.org and chess.com public APIs for importing games