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Latest commit c3f2835 @mcostalba Move ONE_PLY to be 1 instead of 2: final patch!
Convert search() to recurse on a depth divided by 2

No functional change.


Stockfish is a free UCI chess engine derived from Glaurung 2.1. It is not a complete chess program and requires some UCI-compatible GUI (e.g. XBoard with PolyGlot, eboard, Arena, Sigma Chess, Shredder, Chess Partner or Fritz) in order to be used comfortably. Read the documentation for your GUI of choice for information about how to use Stockfish with it.

This version of Stockfish supports up to 128 cores. The engine defaults to one search thread, so it is therefore recommended to inspect the value of the Threads UCI parameter, and to make sure it equals the number of CPU cores on your computer.


This distribution of Stockfish consists of the following files:

  •, the file you are currently reading.

  • Copying.txt, a text file containing the GNU General Public License.

  • src, a subdirectory containing the full source code, including a Makefile that can be used to compile Stockfish on Unix-like systems.

Compiling it yourself

On Unix-like systems, it should be possible to compile Stockfish directly from the source code with the included Makefile.

Stockfish has support for 32 or 64-bit CPUs, the hardware POPCNT instruction, big-endian machines such as Power PC, and other platforms.

In general it is recommended to run make help to see a list of make targets with corresponding descriptions. When not using the Makefile to compile (for instance with Microsoft MSVC) you need to manually set/unset some switches in the compiler command line; see file types.h for a quick reference.

Terms of use

Stockfish is free, and distributed under the GNU General Public License (GPL). Essentially, this means that 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 web site, 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 full source code, or a pointer to where the source code can be found. If you make any changes to the source code, these changes must also be made available under the GPL.

For full details, read the copy of the GPL found in the file named Copying.txt

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