Alternative Chess plays through Fairy-Stockfish, by Fabian Fichter, which is free software under the GNU General Public License version 3 and comes with no warranty.
The app ships the engine rather than calling one elsewhere, so this is the complete corresponding source for both builds it ships. Nothing in the engine has been modified.
fairy-stockfish-2b5d9512.tar.gz2b5d9512 — what anyone playing
on a phone receives, compiled into the app. This is the exact tree the app
compiles, taken from the machine that builds it.fairy-stockfish-nnue.wasm-1.1.11-source.tar.gzfairy-stockfish-nnue.wasm 1.1.11 — what anyone playing in a browser
receives, as WebAssembly.The phone archive is the source those binaries were compiled from.
The browser archive is
fairy-stockfish.wasm
at commit 5589ea54f322e8e76c199440e55ae39fe5d3b09c, tagged
1.1.11-2 — the commit that produced fairy-stockfish-nnue.wasm 1.1.11.
That correspondence was established rather than assumed. The
engine stamps its own source commit into the WebAssembly at compile time, and
the stockfish.wasm served with this app stamps
5589ea54; the npm registry records the same commit as that
release's gitHead; and the release's signed build provenance names
the same tag and commit. The binaries themselves come from the published npm
package, byte for byte — they were not built here.
The full GPL-3.0 text is inside each archive, as Copying.txt,
and is also readable inside the app itself — Settings, then
“Plays through Fairy-Stockfish”.