link to OliThink's page on Chess-Progamming-Wiki
Special thanks to Jim Ablett and Dann Corbit for their support and contribution!

link to OliThink's page on GitHub (5.11.9 sources and executables, can also be downloaded here)

OliThink 5.11.9

New! OliThink talks UCI now! (updated 27. Aug. 2025, UCI protocol, slim version)

Minimalistic chess engine OliThink without any use of external libraries. Engine runs without any chess information. No tablebases, no neural net (NNUE) etc.
ELO about 3000. 128 MB fix Hashsize.

5.11.9(uci): Source with x64 executables for Windows/Linux/MacOSX

5.11.9(xboard): Source with x64 executables for Windows/Linux/MacOSX

5.10.5: Windows x64 Mac OSX x64 Linux x64 Source Code

Translation of OliThink 5 C to java. 5.9.9 is available with an own GUI as standalone application.

5.9.9: Java engine executable (jar) Java Source Code with GUI

Play OliThink5 Java online (Demo)

Start with "java -jar OliThinkGUI.jar" or just doubleclick if your OS is correctly configured.

OliThink Java with GUI executable (jar) (63kb) Vers. 5.9.9

OliThink 5.3.3

Windows x64 Mac OSX x64 Linux x64 Source Code Java Source

Please note that versions 5.4.0 to 5.4.3 and versions before 5.3.3 contain a destabilizing bug.
Check this branch for the fix of either version.

OliThink 4 or before:

(4.1.3 has been fixed for 64bit compile, 3.0.7 for a 3-fold repetition bug, 2.2.3 for a protocol bug)

4.1.3: Mac OSX x64 Linux x64 Windows x64 Source Code

4.1.2: Java Binary (jar) Java Source Code

3.0.7: Mac OSX x64 Linux x64 Windows x64 Source Code

2.2.3: Mac OSX x64 Linux x64 Windows x64 Source Code

New Move Generator OliPerft (Pre OliThink 5)

New Features:

Magic Move Bitboard (Edit: Actually it's Kindergarten Bitboard, an independent invention.)
No piece list, no Array[64] board, just plain bitboard
Simple, easy and short code
One symmetric "doMove" function for doMove and undoMove
Includes "divide" option for debugging
Counts 100 Millions of Moves/second (on a 64bit System 200 Millions, on a modern 64bit CPU 700 Millions (EDIT: Now 1600 Millions))

1.0.8: Source Code Mac OSX x64 Linux x64 Windows x64

Usage: oliperft <depth> <fen>
#oliperft 6 "r3k2r/p1ppqpb1/bn2pnp1/3PN3/1p2P3/2N2Q1p/PPPBBPPP/R3K2R w KQkq - 0 1"

for "divide" just add "-" before the <depth>
#oliperft -6 "r3k2r/p1ppqpb1/bn2pnp1/3PN3/1p2P3/2N2Q1p/PPPBBPPP/R3K2R w KQkq - 0 1"

Important Links for OliThink: