All of the below listed (free) chess engines run fine under the commercial ChessBase, Lokasoft and the freeware Arena.
| Wildcat 7 Strong UCI engine. |
Petir 3.99d Winoard engine by Peter Alloysius. | Naum 2.0 Very strong UCI engine. |
Slow Chess Strong UCI engine with own Interface. |
| The Baron Author: Richard Pijl from the Netherlands. |
Gambit Fruit Another Fruit clone. | ||
| Yace (Y)et (A)nother (C)hess (E)ngine. Paderborn edition. |
The Crazy Bishop written by Remi Coulom. | ||
| Scorpio 1.91 Daniel Shawul. |
Pharaon Franck Zibi. | ||
| Spike 1.1 Very strong program by Volker Böhm and Ralf Schäfer. |
Spike 1.2 Spike tied for the 5th place at the WCCC 2006 in Italy. | ||
| Pseudo 0.7c by Jan Klima. |
Ufim 8.02 by N. Khasanov. | ||
| Glaurung 1.21 by Tord Romstad. |
Queen 3.09 by Leen Ammeraal. | ||
| Delfi 5.0 by Dr. Fabio Cavicchio. |
Jonny 2.83 by Johannes Zwanzger. | ||
| Colossus Resurrection from the past, welcome back Martin Bryant. |
Comet Version B68 by Dr. Ulrich.Tuerke | ||
| Pro Deo 1.0 First Pro Deo version. |
Pro Deo 1.1 And the next one. | ||
| Rybka 1.0 By far the strongest free chess engine available. |
Fruit 2.1 Strong! and with open source. | ||
| Pro Deo 1.2 Ed Schröder's latest and last version. |
Crafty 21.5 Bob Hyatt's World-Famous Crafty. | ||
| Toga II Fruit clone and a good one. |
Zappa Another strong chess engine with own Opening Book. | ||
| Ruffian 1.0 Remember the strorm it caused in 2002? |
Ktulu 4.2 Last freeware version. |