GNU Affero General Public License v3.0
Source:LICENSE.md
Tanmai Chess - read a chess board from a screenshot and find the move Copyright (C) 2026 Tanmay Chanda
This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
This program 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 Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License along with this program. If not, see https://www.gnu.org/licenses/.
The complete licence text is in LICENSE.
What this means in practice
You may use, study, modify and share this software freely. If you distribute it, or a modified version of it, the source must be available under this same licence.
The “Affero” part matters for this project specifically: running a modified version as a network service counts as distribution. Anyone who hosts their own copy of this app, changed in any way, has to make their source available to the people using it. An ordinary GPL would let them keep those changes private as long as they never shipped the code, which for a web app is the whole of the loophole.
Third-party components
This repository bundles or downloads work by other people, under their own terms:
| Component | Licence |
|---|---|
chess.js (inst/js/) |
MIT |
chessboard.js (inst/app/www/) |
MIT |
cburnett piece SVGs (inst/svg/, via python-chess) |
GPL-3.0 |
Poppins (pkgdown/fonts/) |
SIL Open Font License 1.1 |
| Stockfish (installed at build time) | GPL-3.0 |
| lc0 (built at image build time) | GPL-3.0 |
| Maia weights | GPL-3.0 |
Stockfish and lc0 are run as separate processes over UCI rather than linked into this program. Piece art for other sets is fetched at runtime for personal use and is not redistributed here; piece_set_manifest() records each set’s licence.