Universal Chess Interface

The Universal Chess Interface (UCI) is an open communication protocol that enables chess engines to communicate with user interfaces

UCI tells what position the game is in

position command §

position startpos moves e2e4 e7e5 g1f3

• startpos - the normal chess starting position
• moves - followed by a long list of sequential moves

Start from an arbitrary FEN position §

position fen rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1 moves e2e4

• fen - tells the engine the exact board setup using a FEN string

Move Syntax §

• Pawn moves: e2e4, a7a8q (the last letter q = promotion to queen, can also be n, b, r)
• Piece moves: No piece letters just squares
  • Knight from g1 to f3 $\to$ g1f3
  • Bishop from f1 to c4 $\to$ f1c4
• Castling:
  • Kingside castling $\to$ e1g1 (White), e8g8 (Black)
  • Queenside castling $\to$ e1c1 (White), e8c8 (Black)