Best chess engine under permissive free software license

| | August 6, 2015

What is the best chess engine released under permissive free software license? By permissive free software license I mean, that it is legal to incorporate the engine’s code into my project without having to release the source code of my whole project.

5 Responses to “Best chess engine under permissive free software license”

  1. There is a list of available for download engines. And comparison of them.

    Try google some of them and you can find more information about license. For example, you can download previous versions of Rybka and Houdini for free.

    Another list here. And open-source engine Toga II.

    All of them use UCI. To test engines you can type commands:

    position startpos moves e2e4 e7e5 g1f3
    go movetime 1000
  2. My Engine of Choice in the preferred order:

    1) Fruit 2.1
    2) Crafty
    3) Fairy Max

    all of them being very strong, and code is GPL. Even the famous (and commercial) Rybka is said to be based on Fruit’s code though its author denies it.

    And, yes it is legal to reuse their code or improve upon it without going commercial. If you are building commercial applications then it is not allowed under GPL.

  3. MicroMax, HuoChess, Stelka, Robboito are some of the free chess engines without any licensing or restrictions.

  4. Have you looked at the Computer Chess Blog. The source code posted there has no license attached to it.

  5. GNU-chess works with a number of different front ends, and there are web servers that let you play against it in a web browser. Even though the software is GPL, it seems that you might be able to run it as a separate process and have a closed source front end talk to it. This would require careful investigation to see if it’s OK. With GPL you can’t incorporate it, you can’t link it (that’s LGPL), but I think it talks some protocol through pipes which might allow it to run as a server on a local machine. You’d still have to offer source for that piece of the product though.

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