Licences and engine source
ChessMoveScout is built on open-source software. This page lists each part, its licence, and where its source is. Last updated 9 November 2026.
Stockfish 19 (GNU GPL v3)
The best move calculator and the analysis board run Stockfish 19, the free and open-source chess engine by the Stockfish developers, in the Stockfish.js 19.0.1 WebAssembly build by Nathan Rugg (the "lite, single-threaded" build). Stockfish and Stockfish.js are licensed under the GNU General Public License version 3.
The files we serve are /assets/engine/stockfish-19-lite-single.js and /assets/engine/stockfish-19-lite-single.wasm, unchanged from the npm package stockfish@19.0.1. You may copy, change and share them under the GPL.
Complete source for the engine build
The Corresponding Source for the engine files above is hosted on this site, so it stays available as long as we serve the engine:
| File | Size | SHA-256 |
|---|---|---|
| Copying.txt | 35 KB | 0b383d5a63da644f… |
| README.txt | 2 KB | bc8f90ad4b7df2d8… |
| nn-61e7af4bb97d.nnue | 1.1 MB | 61e7af4bb97d51ee… |
| stockfish.js-v19.0.1.tar.gz | 416 KB | a18aa8a871f52650… |
The source archive is Stockfish.js at its release tag v19.0.1 (commit 8d9ca57). It includes the engine source, the build script and the instructions. The lite build embeds the neural network file nn-61e7af4bb97d.nnue, which the build downloads; we host that exact file too (its SHA-256 starts with its name, as Stockfish requires). Full checksums are in SHA256SUMS, and build notes in README.txt.
Upstream: Stockfish.js v19.0.1 and the official Stockfish project. If a link here stops working, email hello@chessmovescout.com and we will send the source.
Our own page code that talks to the engine (/assets/js/) is served unminified, so you can read it. It sends standard UCI text commands to the engine running in a separate worker.
chess.js (BSD 2-Clause)
Move rules, FEN and PGN handling use chess.js 1.4.0, Copyright (c) 2025, Jeff Hlywa. Redistribution and use in source and binary forms, with or without modification, are permitted under the BSD 2-Clause licence; the notice is kept at the top of /assets/js/chess.js. The software is provided "as is", without any warranty.
Fonts (SIL Open Font License 1.1)
- Sora and DM Sans, for text.
- Noto Sans Symbols 2 (Copyright 2022 The Noto Project Authors), for the chess pieces; we serve only the six chess-piece characters.
All three are under the SIL Open Font License 1.1 and are served from this site.
Names
Stockfish is the name of the open-source engine project; ChessMoveScout is not made or endorsed by the Stockfish developers. Chess.com and Lichess are named only to say where games can be copied from; we are not affiliated with either.
This page is our reading of the licences, not legal advice.