KOTSUMORI AI Chess uses the following open-source components.

Chessground 10.1.1
Copyright Lichess contributors
License: GPL-3.0-or-later
Source: https://github.com/lichess-org/chessground/tree/v10.1.1
License text: /licenses/Chessground-GPL-3.0.txt

Stockfish.js 18.0.8 / Stockfish 18 Lite WASM
Copyright Chess.com, LLC and Stockfish contributors
License: GPL-3.0
Source: https://github.com/nmrugg/stockfish.js/tree/v18.0.8
Stockfish source: https://github.com/official-stockfish/Stockfish/tree/sf_18
License text: /licenses/Stockfish-GPL-3.0.txt

chess.js 1.4.0
Copyright Jeff Hlywa and contributors
License: BSD-2-Clause
Source: https://github.com/jhlywa/chess.js/tree/v1.4.0
License text: /licenses/chess.js-BSD-2-Clause.txt

KOTSUMORI integration source:
https://github.com/dvzad/kotsumori/tree/master/src/chess-tool.js
https://github.com/dvzad/kotsumori/tree/master/src/chess-engine.js