Stockfish
A free and strong UCI chess engine.
Explore Stockfish docs »
Report bug
·
Open a discussion
·
Discord
·
Blog
Overview
Stockfish is a free and strong UCI chess engine derived from
Glaurung 2.1 that analyzes chess positions and computes the optimal moves.
Stockfish does not include a graphical user interface (GUI) that is required
to display a chessboard and to make it easy to input moves. These GUIs are
developed independently from Stockfish and are available online. Read the
documentation for your GUI of choice for information about how to use
Stockfish with it.
See also the Stockfish documentation for further usage help.
Files
This distribution of Stockfish consists of the following files:
-
README.md, the file you are currently reading.
-
Copying.txt, a text file containing the GNU General Public
License version 3. -
AUTHORS, a text file with the list of authors for the project.
-
src, a subdirectory containing the full source code, including a
Makefile that can be used to compile Stockfish on Unix-like systems. -
a file with the .nnue extension, storing the neural network for the NNUE
evaluation. Binary distributions will have this file embedded.
Contributing
See Contributing Guide.
Donating hardware
Improving Stockfish requires a massive amount of testing. You can donate your
hardware resources by installing the Fishtest Worker and viewing
the current tests on Fishtest.
Improving the code
In the chessprogramming wiki, many techniques used in
Stockfish are explained with a lot of background information.
The section on Stockfish describes many features
and techniques used by Stockfish. However, it is generic rather than
focused on Stockfish\’s precise implementation.
The engine testing is done on Fishtest.
If you want to help improve Stockfish, please read this guideline
first, where the basics of Stockfish development are explained.
Discussions about Stockfish take place these days mainly in the Stockfish
Discord server. This is also the best place to ask questions
about the codebase and how to improve it.
Compiling Stockfish
Stockfish has support for 32 or 64-bit CPUs, certain hardware instructions,
big-endian machines such as Power PC, and other platforms.
On Unix-like systems, it should be easy to compile Stockfish directly from the
source code with the included Makefile in the folder src. In general, it is
recommended to run make help to see a list of make targets with corresponding
descriptions. An example suitable for most Intel and AMD chips:
cd src
make -j profile-build
Detailed compilation instructions for all platforms can be found in our
documentation. Our wiki also has information about
the UCI commands supported by Stockfish.
Terms of use
Stockfish is free and distributed under the
GNU General Public License version 3 (GPL v3). Essentially,
this means you are free to do almost exactly what you want with the program,
including distributing it among your friends, making it available for download
from your website, selling it (either by itself or as part of some bigger
software package), or using it as the starting point for a software project of
your own.
The only real limitation is that whenever you distribute Stockfish in some way,
you MUST always include the license and the full source code (or a pointer to
where the source code can be found) to generate the exact binary you are
distributing. If you make any changes to the source code, these changes must
also be made available under GPL v3.
Acknowledgements
Stockfish uses neural networks trained on data provided by the Leela Chess Zero
project, which is made available under the Open Database License (ODbL).
