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Blunder is an open-source UCI compatible chess engine. The philosophy behind Blunder's design is for the code to be straightforward and easy to read, so that others can benefit from the project.

Version Estimated Rating (Elo) CCRL Rating (Elo) WAC1 IQ6 2
1.0.0 1400 N/A N/A N/A
2.0.0 1570 N/A N/A N/A
3.0.0 1782 N/A N/A N/A
4.0.0 1832 1734 N/A N/A
5.0.0 2000 2080 N/A N/A
6.0.0 2200 N/A N/A N/A
6.1.0 2200 2155 N/A N/A
7.0.0 2280 N/A 279 2477
7.1.0 2395 N/A N/A N/A
7.2.0 2395 2425 N/A N/A
7.3.0 2450 N/A N/A N/A

1 Win At Chess

2 IQ6 Test


Builds for Windows, Linux, and MacOS are included with each release of Blunder. However, if you prefer to build Blunder from scratch the steps to do so are outlined below.

Visit Golang download page, and install Golang using the download package appropriate for your machine. To make using the Golang compiler easier, make sure that if the installer asks, you let it add the Golang compiler command to your path.

Your installation should be up and running in about 5-7 minutes, and from there, you need to open up a terminal/powershell/ command line, navigate to blunder/blunder, and run go build. This will create an executable for your computer, which you should then able to run.

Alternatively, if the make build automation tool is installed on your computer (it comes standard on most Linux systems), simply download this repository's zip file, unzip it, navigate to the primary folder, and run make from the command line. An executable for Windows, Linux, and MacOS will be built and placed inside of the primary directory.

If you're on a windows platform, you'll need to run make build-windows instead.


Blunder, like many chess engines, does not include its own GUI for chess playing, but supports something known as the UCI protocol. This protocol allows chess engines, like Blunder, to communicate with different chess GUI programs.

So to use Blunder, it's reccomend you install one of these programs. Popular free ones include:

Once you have a program downloaded, you'll need to follow that specfic programs guide on how to install a chess engine. When prompted for a command or executable, direct the GUI to the Golang exectuable you built.



The changelog of features for Blunder can be found in the docs/


Although Blunder is an orginal project, there are many people without whom Blunder would not have been finished. The brief listing is included here (in no particular order). For the full listing, with elaborations, see docs/

My girlfriend, Marcel Vanthoor, Hart Gert Muller, Sven Schüle, J.V. Merlino, Niels Abildskov, 
Maksim Korzh, Erik Madsen, Pedro Duran, Nihar Karve, Rhys Rustad Elliott, Lithander, 
Jonatan Pettersson, Rein Halbersma, Tony Mokonen, SmallChess, Richard Allbert, Spirch, and
the Stockfish Developers.

These credits will be updated from time to time as I remember or encounter more people who have helped me in Blunder's development.


Blunder is licensed under the MIT license.


A UCI compatible chess engine written in Golang




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