A multi-threaded Stockfish that runs in Chrome using PNaCl. Also see stockfish.js as a fallback.

Unmaintained, since PNaCl is deprecated and will be replaced by WebAssembly.

About 500 KB uncompressed, 400 KB gzipped.

See nacl/index.html for an example.

1. Install the NaCl SDK and setup an environment variable NACL_SDK_ROOT=path/to/nacl_sdk/pepper_49
2. cd nacl
3. make

• Start an HTTP server, for instance python3 -m http.server ./nacl
• Browse http://127.0.0.1:8080/ in chrome

• Replace src/main.cpp with src/nacl.cpp.
• Turn UCI::loop into UCI::command.
• Remove Syzygy tablebases.
• Recover from (all but minimum) transposition table allocation failures.

Thanks to @exoticorn for providing a PNaCl module for the older Stockfish 5.