UCI-capable Crafty built on upstream Crafty 25.6 — the classic engine by Dr. Robert Hyatt, usable directly in modern GUIs (Arena, Cute Chess, Nibbler, BanksiaGUI, ChessBase, …) alongside its original WinBoard/xboard and native console interfaces (auto-detected from the first command).
This is the 25.6 successor to the 25.2-based v25.2.1 UCI release — the entire UCI conversion re-applied on the newer Crafty 25.6 engine base.
Downloads — pick by your CPU
| File | Tier | Requires |
|---|---|---|
crafty-25.6.1-win-x86-64-v3.exe |
Cutting-edge (fastest) | AVX2 / BMI2 — Intel Haswell (2013+) / AMD Zen |
crafty-25.6.1-win-x86-64-v2.exe |
In-between | SSE4.2 / popcnt (2008+) |
crafty-25.6.1-win-x86-64.exe |
Basic / max compatibility | any 64-bit x86 CPU |
All are 64-bit Windows builds compiled with -O3 + profile-guided optimization (PGO), with Syzygy tablebase support and multi-threading (up to 64 threads). If unsure, try v3 first; if it won't launch, fall back to v2, then the basic build.
Highlights
- Now based on upstream Crafty 25.6 (the previous UCI release was 25.2) — the newer search/evaluation from Bob Hyatt, with the UCI layer re-applied on top.
- Full UCI protocol:
position,go(depth / movetime / clock / infinite / ponder),stop,ponderhit, streaminginfo(incl.seldepthandcurrmove/currmovenumber),bestmove, and options: Hash, Threads, Ponder, SyzygyPath, OwnBook/BookFile, Move Overhead. - WinBoard/xboard and native console interfaces unchanged — every UCI change is additive and mode-gated.
Notes
- Crafty is © Robert M. Hyatt — free for personal use (see README and the source header); not OSI-licensed.
- 32-bit x86 build not included.
- Reproducible from source via
scripts/build-releases.sh. Building Crafty 25.6 on gcc 14+ / clang requires-std=gnu17(its bundled Syzygy code predates the C23boolkeyword) — already set in the build script, Makefile, and README commands. - Validated with the UCI transcript test suite (57 assertions) and perft (move-generation) checks.