Licenses

This site uses the following open source software. Thank you!

Stockfish 19 (stockfish.js, lite single-thread WASM)

Computer opponents and game analysis (runs in your browser)

License: GNU GPL v3 · Source code

Used unmodified. Source of the WebAssembly build: https://github.com/nmrugg/stockfish.js (version 19.0.1). The license text is shipped with the engine files.

GPL v3 license text

chess.js

Chess rules and move validation

License: BSD-2-Clause, Copyright (c) 2025, Jeff Hlywa · Source code

glicko2.js

Rating calculation

License: MIT · Source code

Socket.IO

Online game connection

License: MIT · Source code

Next.js

Site infrastructure

License: MIT · Source code

React

Interface

License: MIT · Source code

Arctic

Sign in with Google

License: MIT · Source code

Inter and Plus Jakarta Sans fonts

Fonts

License: SIL Open Font License 1.1 · Source code

The piece drawings and interface design belong to the site.