Houdini Chess Engine
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Welcome to the Houdini Chess Engine home page. Houdini is a state-of-the-art chess engine for Windows combining outstanding positional evaluation with the most sophisticated search algorithm.

The name Houdini was chosen because of the engine's positional style, its tenacity in difficult positions and its ability to defend stubbornly and escape with a draw – sometimes by the narrowest of margins. On the other hand Houdini will often use razor-sharp tactics to deny its opponents escape routes when it has the better position.

Each Houdini release since December 2010 has been leading the major computer chess rating lists and has been widely considered to be the strongest chess engine money can buy. From numerous interviews it appears that many top Grand Masters including chess World Champions use and appreciate Houdini.

The Chess Club Live Facebook page phrased it like this: "If there ever was a computer descendant of the romantic players like Morphy, Anderssen, Spielmann, Marshall, Bogoljubow, Tal, Nezhmetdinov, Shirov, Morozevich it would be Houdini. Houdini is the current World number 1 chess engine and plays in a very romantic style."

Houdini 6: The strongest engine in the world

Houdini 6 continues the impressive surge made by its predecessor by adding another 50 to 60 Elo in strength, to become once again the strongest engine that money can buy. This playing strength increase means that Houdini 6 is stronger than Houdini 5 using twice the time; or in other words, upgrading to Houdini 6 is like doubling the computational power of your computer for chess.

Every aspect of the engine has been thoroughly reviewed and refined: evaluation, search, time management and table base usage. Houdini 6 makes better use of multiple threads and will be particularly strong on hardware with many cores. To take into account the recent availability of mainstream processors with 8 cores, Houdini 6 Standard version now supports up to 8 threads. On high-end hardware Houdini 6 Pro can make use of up to 128 threads.

The evaluations have again been calibrated to correlate directly with the win expectancy in the position. A +1.00 pawn advantage gives a 75% chance of winning the game against an equal opponent at blitz time control. At +1.50 the engine will win 90% of the time, and at +2.50 about 99% of the time. To win nearly 50% of the time, you need and advantage of about +0.60 pawn.

The enhanced Tactical Mode turns Houdini 6 into the most impressive position solver ever, improving on the records the previous Houdini versions set for solving tactical test suites. When running multiple threads the tactical mode can now be activated for only some of the threads.

The on-line Houdini Chess Engine User's Manual provides clear and detailed instructions so that you can effortlessly leverage your chess analysis capabilities.

Houdini 6 Download Versions for Windows

Houdini is written for Windows and will run on any not too ancient Windows version. On Linux systems you can run Houdini using Wine without any significant performance loss. On Apple computers a Virtual Machine (e.g. Parallels Desktop) is required to run Houdini.

Two Houdini 6 versions are available:
Houdini 6 Standard Best option for most users with main-stream hardware.
Supports up to 8 threads and 4 GB of hash.
Houdini 6 Pro For high-end users with powerful hardware. Supports up to 128 threads and 128 GB of hash memory, Large Memory Pages, NUMA-architecture and Nalimov bases.
Click here for more information about Houdini Pro.


Direct support by the author of Houdini, Robert Houdart, is available by e-mail at the address [email protected].

Before mailing please check out the on-line Houdini Chess Engine User's Manual with installation tips and Frequently Asked Questions.

Version History

Houdini 6

  • Houdini 6.03 (20171120): Correction for incorrect detection of stalemate in positions with white pawn capture moves.
  • Houdini 6.02 (20171001): Maintenance update with Polyglot book support.
  • Houdini 6.01 (20170924): Maintenance update with Nalimov EGTB correction and new output option.
  • Houdini 6 (20170915): Major new version. Improved search and evaluation (+50-60 Elo), enhanced multi-threading.

Houdini 5

  • Houdini 5.01 (20161115): Maintenance update with some interface corrections and improvements.
  • Houdini 5 (20161107): Major new version, about 200 Elo stronger. Rewritten evaluation function, deeper search.

Houdini 4

  • Houdini 4 (20131125): Major new version. Improved search and evaluation (+50 Elo), 6-men Syzygy table bases.

Houdini 3

  • Houdini 3 (20121015): Major new version. Improved search and evaluation (+50 Elo), Tactical Mode, Scorpio bitbases.

Houdini 2

  • Houdini 2.0c (20111120): Maintenance update with minor bug corrections and new analysis options.
  • Houdini 2.0b (20111007): Maintenance update with minor bug corrections and Nalimov EGTB support.
  • Houdini 2.00 (20110901): Improved analysis capabilities, enhanced search and evaluation.

Houdini 1.5

  • Houdini 1.5a (20110115): Maintenance update with work-arounds for Fritz GUI and other minor improvements.
  • Houdini 1.50 (20101215): Improved search and evaluation. Gaviota Table Base Support.

Houdini 1.0

  • Houdini 1.03a (20100717): Bug fix for Multi-PV.
  • Houdini 1.03 (20100715): Multi-PV, searchmove and large page support. Improved evaluation function.
  • Houdini 1.02 (20100618): SMP and hash collision bug fixes. Work-around for Shredder GUI.
  • Houdini 1.01 (20100601): Bug fixes. Improved search algorithm.
  • Houdini 1.00 (20100515): First release.


An invaluable resource for any chess engine author is the excellent Chess Programming Wiki.

The Syzygy TB probing code used by Houdini is © Ronald de Man, the Nalimov EGTB probing code is © Eugene Nalimov.