Guides / Stockfish 19 in your browser: Lite, Full and threads
Stockfish 19 in your browser: Lite, Full and threads
GChess Review has no analysis server. The chess engine, Stockfish 19, is compiled to WebAssembly and runs inside your browser tab. This page explains the choices that follow from that.
Lite and Full
- Stockfish 19 Lite is about 1.6 MB. It loads with the page and is used by default. Its neural network is smaller, and it is still far stronger than any human player.
- Stockfish 19 Full is about 99 MB, with the full-size network. It is downloaded only when you ask for it in the engine settings, and kept in your browser's cache so it is never downloaded twice. You can remove it from the same place.
Threads
Stockfish searches faster on several processor cores at once. In a browser that needs SharedArrayBuffer, which browsers only allow on pages that isolate themselves from other sites. GChess Review is served that way, so in a supporting browser the engine runs on several threads. Where that is not possible, it falls back to a single-threaded build, and on very old browsers to an asm.js build, slower but still working.
The choice is made by testing what the browser can actually do, never by guessing from its name.
What is stored on your device
Only what you would expect: the Full engine if you download it, your settings, your puzzle progress, your games against the bots, and the usernames you searched. Clearing the site's data in your browser removes all of it. The privacy page lists every item.
Licence
Stockfish is free software under the GNU General Public License v3. The engine files are served with their licence and a pointer to their source, listed on the licences page.