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Getting Started


  • To help the project by donating GPU time, here’s the gist of what you need to do:
  1. Download and install the Client and Engine
  2. Run the client.exe

The client will run games and arrange all communication with the learning server. Thanks for contributing!

To go a bit more in depth, Lc0 has three main parts:

NAME FILE Function Needed for Contributing Needed for Playing
Engine lc0.exe Does the tree search and calls the NN to get evaluations YES YES
Network (NN) Varies e.g. weights_run1_62114.pb.gz Stores the Neural Net’s evaluation function NO YES
Client client.exe Gets the latest network from the server, generates self-play games, and uploads the training data to the server YES NO
  • To play or analyze games with Lc0, you don’t need client.exe, but you do need the engine lc0.exe and a network file. The best way to do this is using a chess GUI. See the guide in our blog.


Just download the relevant version for your machine and place the downloads in the same directory to be able to contribute to leela’s learning process or to analyse games.


Can be downloaded from https://github.com/LeelaChessZero/lczero-client/releases

  • Windows –> client.exe
  • Linux –> client_linux
  • Mac –> client_mac
  • Note: recent versions of engine package include client.exe


  • Mac/Linux –> must be compiled by user (refer to the [[README.md|https://github.com/LeelaChessZero/lc0#mac]] in github )
  • Windows –> download the latest from https://github.com/LeelaChessZero/lc0/releases
    • CPU only : lc0--windows-blas.zip
    • Nvidia GPU : lc0--windows-cuda-zip
    • Other GPU cases: lc0–-windows-opencl.zip
  • [[Changelog|https://github.com/LeelaChessZero/lc0/blob/master/changelog.txt]] between different versions


The client will already download the latest network for contributing games. If you want, you can download a specific version of a network. Download a network from http://training.lczero.org/networks or see best nets for an overview of the best nets for your specific hardware conditions.

  • The name will be some long hash string, for example: b82f0b34b96c8f38f68ee97703b4149ab976122ca9bed6120f9dea88d733d266
  • Rename to “weights” (for convenience).
  • Place in the same directory with the lc0 application. On a Mac this is /Users/[username]/lc0/build/release/.
  • The file will be found automatically after opening lc0 in the command line.

Get started analyzing positions

You can analyse games in the engine console as follows:

  • Open the lc0 application.
  • Enter the command “go nodes 100” in the terminal.
  • lc0 will begin a configuration process, which will only happen once. Then it will analyze the starting position for 100 nodes.
  • To increase the quality of analysis, use more nodes.
  • To analyse a position, type for example, “position startpos moves e2e4 e7e5”, where the moves lead to the desired position. Then use “go nodes [number]” again.
  • To analyse a specific position you can give the engine a FEN position “position fen 4k3/8/8/8/8/8/4P3/4K3 w - - 5 39”. Then use “go nodes 100”.

Graphical interface for analyses

With nibbler there is now also a GUI available to help analyse games. You can find the latest version of nibbler at https://github.com/fohristiwhirl/nibbler


  • For easier debug, verify install by running from command line (cmd.exe)
    • cd to directory with lc0.exe.
    • run lc0.exe --logfile=log.txt
      • Most recent weights file in that directory will be used automatically.
      • Add --weights=c:\path\to\weights_476.txt.gz to specify manually.
    • Example expected output:
|   _ | |
|_ |_ |_| built Jul  8 2018
  • Type go nodes 100
  • Example expected output:
go nodes 100
Found network file: C:\Users\aolsen\Desktop\Engines\lc0-win-20180708-cuda92-cudnn714/weights_476.txt.gz
Creating backend [cudnn]...
info depth 2 seldepth 2 time 28 nodes 2 score cp 21 hashfull 0 nps 71 pv c2c4 g8f6
info depth 2 seldepth 3 time 39 nodes 4 score cp 19 hashfull 0 nps 102 pv c2c4 e7e5 g2g3
info depth 2 seldepth 4 time 56 nodes 15 score cp 20 hashfull 0 nps 267 pv c2c4 c7c5 g1f3 g8f6
info depth 2 seldepth 5 time 73 nodes 34 score cp 20 hashfull 0 nps 465 pv c2c4 c7c5 g1f3 g8f6 b1c3
info depth 2 seldepth 6 time 92 nodes 73 score cp 20 hashfull 0 nps 793 pv c2c4 c7c5 g1f3 g8f6 b1c3 e7e6
info depth 2 seldepth 7 time 111 nodes 121 score cp 20 hashfull 0 nps 1090 pv c2c4 c7c5 g1f3 g8f6 b1c3 b8c6 d2d4
info depth 2 seldepth 7 time 114 nodes 121 score cp 20 hashfull 0 nps 1061 pv c2c4 c7c5 g1f3 g8f6 b1c3 b8c6 d2d4
bestmove c2c4
  • type quit to exit the program.
  • Common problems
    • lc0.exe exits without printing anything
      • Double check you have cublas64_100.dll, cudart64_100.dll, and cudnn64_7.dll in the same directory as lc0.exe
    • CUDA driver version is insufficient for CUDA runtime version
      • You need 411.31 or newer. Download latest from nvidia’s website.
    • error Network weights file not found
      • Download the latest weights from http://training.lczero.org/networks and place in the same directory as lc0.exe.
      • OR: point to the weights using --weights=c:\path\to\weights_run2_32282.pb.gz
    • If there are other problems, please upload log.txt to the discord chat #help channel.


Join the discord for quick help, it is usually very active.

Last Updated: 2020-08-30