logo Devel Chess Engine


Devel is a free UCI engine for Windows, written by Per Skjerpe. The program works well with Arena and with other UCI-compatible programs like Fritz and Chessbase. The program is a 32-bit application for a single processor system. Default hash table is 256 MB, configurable up to 2048 MB. Principal variation search (PVS) with multi-PV option. Supports all common time controls, but never uses pondering (cheating by thinking on opponent's time).

Download the newest version Devel 2.0000 (released March 2018). Its playing strength is ~ ELO 2725, see CCRL 40/40 (40 moves in 40 minutes) or CCRL 40/4 (40 moves in 4 minutes).

You may also download the older version Devel 1.8090 (released September 2017). Its playing strength is ~ ELO 2700.

I am grateful to Graham Banks and Sergio Martinez at CCRL for taking the time to test Devel!


All source code is original, but many ideas have been taken from other programs.

The static evaluation function resembles that of classical Chess 4.5, the ancestor of all modern chess programs. This old program was described in detail by David J. Slate and Lawrence R. Atkin: Chess 4.5-The Northwestern University chess program in the book "Chess Skill in Man and Machine", by Peter W. Frey (ed.), Springer-Verlag, 1983.

The source code of the following programs I found very useful:

In Devel, evaluation of king safety is quite similar to that of Fruit (and Stockfish) and evaluation of passed pawns is nearly the same as in Stockfish.


Devel is written in C++. The internal data structure is quite straight-forward. The chess board is embedded within a convenient 16x16 integer array, in the reverse direction there are arrays giving the placement of pieces on the board. This data structure is similar to that of Fruit. The search is recursive with an expectation window (alpha-beta pruning) and quiescence search for nodes beyond nominal depth. The most common pruning techniques are used, including razoring, futility pruning, null move pruning.


Contact: per.skjerpe@lyse.net


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Last update: 29 November 2019