EPD opening book generator based on Stockfish variant forks.
Bookgen extends Fairy-Stockfish by the possibility of automatically generating opening books for all supported chess variants, including standard chess, crazyhouse, giveaway/suicide chess, atomic chess, and more. There are separate versions based on Fairy-Stockfish (e.g., for Shogi, etc.), multi-variant Stockfish, official Stockfish, for Seirawan chess, Shatranj, and Makruk that can be found on the respective branches. Several methods for generation and filtering of positions in FEN format are supported. The output format is EPD.
See the Wiki for documentation and usage examples.