OpenChess

November 9, 2016: Houdini 5 has been released - Get it today! [Houdini at work © BT07]

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 5 today!

Released nearly 3 years after the previous version, the eagerly anticipated Houdini 5 is a rejuvenated and vastly improved engine.

Incorporating many new techniques and ideas developed over the past three years, Houdini 5 is about 200 Elo stronger than its predecessor. An important contributor to this giant leap in strength is the completely rewritten positional evaluation function. More aggressive King safety and sophisticated piece mobility are the keys to Houdini 5's unique playing style, combining aggressive ideas with sound positional judgment and plans.

By being more selective in its move choices, Houdini 5 now searches significantly deeper than before. This pays huge dividends in every stage of the game, but particularly in end games. For the best end game play, the new Houdini continues to support Syzygy end base tables, which can now be combined with the Nalimov tables to find the shortest path to mate.

The new Houdini implements the so-called "lazy SMP" algorithm and performs better than before on hardware with multiple processor cores. Up to 128 threads are now supported by the Houdini 5 Pro engine.

All major features of previous Houdini versions are still available: multi-PV analysis with user-definable evaluation threshold, Chess960 support and Persistent Hash (saving analysis results to a disk file for later reuse). The unique Tactical Mode has been updated and is now stronger than ever to find tactical solutions in positions.

A development version of Houdini 5 achieved a resounding victory with a score of 56/62 (50 wins and 12 draws) in the TCEC Season 9 Rapid tournament that featured the best 32 engines in the world. The final release version of Houdini 5 is about 30 Elo stronger than the engine that played in the TCEC tournament.

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 5

Houdini 5 (20161107): Major new version, about 200 Elo stronger. Rewritten evaluation function, deeper search.