Houdini Chess Engine
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September 15, 2017: Houdini 6 has been released - Get it today!

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."

Get the new Houdini 6 today!

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 download-only versions are available:
Houdini 6 Standard
€39.95 +VAT*
Best buy for most users with main-stream hardware.
Supports up to 8 threads and 4 GB of hash.
Houdini 6 Pro
€59.95 +VAT*
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.
*VAT will be added for customers from EU member states.

Special Upgrade Promo for Houdini 5 Users: Use the Upgrade Order Page to receive a 20% discount!
Limited-time offer extended until October 31, 2017 for owners of Houdini 5 licenses purchased from our shop.

If you have purchased Houdini 5 from our shop in August or September 2017 you are entitled to a free upgrade to Houdini 6. Please send us an e-mail to get your free upgrade.

The Houdini 6 download link and serial number will be sent to you by e-mail within 24 hours of purchase. Note that during installation you'll require an internet access to activate the product.

If you haven't received our purchase confirmation mail within 24 hours, please check your spam folder first, and if the mail is not there please contact us immediately via the support e-mail address [email protected]. In particular Gmail has the nasty habit of putting the purchase confirmation mail in the spam folder, most of the "did not get the license" requests we receive are coming from Gmail users.

Purchasing Houdini 6 will entitle you to all updates and corrections made to Houdini 6, direct e-mail support by the Houdini author and discounts to future versions of Houdini.

Too expensive? You can still download the free Houdini 1.5 which at the time of the Houdini 6 release remains one of the stronger free chess engines.

Support

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 6.02 (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.

Acknowledgements

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.