Rybka 4 is the world champion of chess engines with a rating of 3250+ points ELO. The main developer of the program - international master Vasik Rajlich (Hungary) has inserted the algorithms of positional estimation into it which are as close to the chess-player's style of thinking as possible.

Rybka is a UCI chess engine, which means that you can use it with almost any modern chess user interface such as Aquarium, Chess Assistant, Shredder, Fritz, Arena, Chessbase, ChessPartner, etc.

Rybka 4 UCI uses one processor/core regardless of how many cores the hardware may have. With that limitation it also runs on all processors under the Windows operating system.

System requirements: PC, 256 MB RAM, 4 GB of free disk space, Windows 7/XP/Vista