python-chess is a chess library for Python, with move generation, move validation, and support for common formats. This is the Scholar's mate in python-chess:

>>> import chess

>>> board = chess.Board()

>>> board.legal_moves  # doctest:  ELLIPSIS
<LegalMoveGenerator at ... (Nh3, Nf3, Nc3, Na3, h3, g3, f3, e3, d3, c3, ...)>
>>> chess.Move.from_uci("a8a1") in board.legal_moves
False

>>> board.push_san("e4")
Move.from_uci('e2e4')
>>> board.push_san("e5")
Move.from_uci('e7e5')
>>> board.push_san("Qh5")
Move.from_uci('d1h5')
>>> board.push_san("Nc6")
Move.from_uci('b8c6')
>>> board.push_san("Bc4")
Move.from_uci('f1c4')
>>> board.push_san("Nf6")
Move.from_uci('g8f6')
>>> board.push_san("Qxf7")
Move.from_uci('h5f7')

>>> board.is_checkmate()
True

>>> board
Board('r1bqkb1r/pppp1Qpp/2n2n2/4p3/2B1P3/8/PPPP1PPP/RNB1K1NR b KQkq - 0 4')

Requires Python 3.7 . Download and install the latest release:

pip install chess

• Core
• PGN parsing and writing
• Polyglot opening book reading
• Gaviota endgame tablebase probing
• Syzygy endgame tablebase probing
• UCI/XBoard engine communication
• Variants
• Changelog

• Includes mypy typings.

• IPython/Jupyter Notebook integration. SVG rendering docs.

  >>> board  # doctest:  SKIP

  

• Chess variants: Standard, Chess960, Suicide, Giveaway, Atomic, King of the Hill, Racing Kings, Horde, Three-check, Crazyhouse. Variant docs.

• Make and unmake moves.

  >>> Nf3 = chess.Move.from_uci("g1f3")
  >>> board.push(Nf3)  # Make the move
  
  >>> board.pop()  # Unmake the last move
  Move.from_uci('g1f3')

• Show a simple ASCII board.

  >>> board = chess.Board("r1bqkb1r/pppp1Qpp/2n2n2/4p3/2B1P3/8/PPPP1PPP/RNB1K1NR b KQkq - 0 4")
  >>> print(board)
  r . b q k b . r
  p p p p . Q p p
  . . n . . n . .
  . . . . p . . .
  . . B . P . . .
  . . . . . . . .
  P P P P . P P P
  R N B . K . N R

• Detects checkmates, stalemates and draws by insufficient material.

  >>> board.is_stalemate()
  False
  >>> board.is_insufficient_material()
  False
  >>> board.outcome()
  Outcome(termination=<Termination.CHECKMATE: 1>, winner=True)

• Detects repetitions. Has a half-move clock.

  >>> board.can_claim_threefold_repetition()
  False
  >>> board.halfmove_clock
  0
  >>> board.can_claim_fifty_moves()
  False
  >>> board.can_claim_draw()
  False

  With the new rules from July 2014, a game ends as a draw (even without a claim) once a fivefold repetition occurs or if there are 75 moves without a pawn push or capture. Other ways of ending a game take precedence.

  >>> board.is_fivefold_repetition()
  False
  >>> board.is_seventyfive_moves()
  False

• Detects checks and attacks.

  >>> board.is_check()
  True
  >>> board.is_attacked_by(chess.WHITE, chess.E8)
  True
  
  >>> attackers = board.attackers(chess.WHITE, chess.F3)
  >>> attackers
  SquareSet(0x0000_0000_0000_4040)
  >>> chess.G2 in attackers
  True
  >>> print(attackers)
  . . . . . . . .
  . . . . . . . .
  . . . . . . . .
  . . . . . . . .
  . . . . . . . .
  . . . . . . . .
  . . . . . . 1 .
  . . . . . . 1 .

• Parses and creates SAN representation of moves.

  >>> board = chess.Board()
  >>> board.san(chess.Move(chess.E2, chess.E4))
  'e4'
  >>> board.parse_san('Nf3')
  Move.from_uci('g1f3')
  >>> board.variation_san([chess.Move.from_uci(m) for m in ["e2e4", "e7e5", "g1f3"]])
  '1. e4 e5 2. Nf3'

• Parses and creates FENs, extended FENs and Shredder FENs.

  >>> board.fen()
  'rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1'
  >>> board.shredder_fen()
  'rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w HAha - 0 1'
  >>> board = chess.Board("8/8/8/2k5/4K3/8/8/8 w - - 4 45")
  >>> board.piece_at(chess.C5)
  Piece.from_symbol('k')

• Parses and creates EPDs.

  >>> board = chess.Board()
  >>> board.epd(bm=board.parse_uci("d2d4"))
  'rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - bm d4;'
  
  >>> ops = board.set_epd("1k1r4/pp1b1R2/3q2pp/4p3/2B5/4Q3/PPP2B2/2K5 b - - bm Qd1 ; id \"BK.01\";")
  >>> ops == {'bm': [chess.Move.from_uci('d6d1')], 'id': 'BK.01'}
  True

• Detects absolute pins and their directions.

• Reads Polyglot opening books. Docs.

  >>> import chess.polyglot
  
  >>> book = chess.polyglot.open_reader("data/polyglot/performance.bin")
  
  >>> board = chess.Board()
  >>> main_entry = book.find(board)
  >>> main_entry.move
  Move.from_uci('e2e4')
  >>> main_entry.weight
  1
  
  >>> book.close()

• Reads and writes PGNs. Supports headers, comments, NAGs and a tree of variations. Docs.

  >>> import chess.pgn
  
  >>> with open("data/pgn/molinari-bordais-1979.pgn") as pgn:
  ...     first_game = chess.pgn.read_game(pgn)
  
  >>> first_game.headers["White"]
  'Molinari'
  >>> first_game.headers["Black"]
  'Bordais'
  
  >>> first_game.mainline()  # doctest:  ELLIPSIS
  <Mainline at ... (1. e4 c5 2. c4 Nc6 3. Ne2 Nf6 4. Nbc3 Nb4 5. g3 Nd3#)>
  
  >>> first_game.headers["Result"]
  '0-1'

• Probe Gaviota endgame tablebases (DTM, WDL). Docs.

• Probe Syzygy endgame tablebases (DTZ, WDL). Docs.

  >>> import chess.syzygy
  
  >>> tablebase = chess.syzygy.open_tablebase("data/syzygy/regular")
  
  >>> # Black to move is losing in 53 half moves (distance to zero) in this
  >>> # KNBvK endgame.
  >>> board = chess.Board("8/2K5/4B3/3N4/8/8/4k3/8 b - - 0 1")
  >>> tablebase.probe_dtz(board)
  -53
  
  >>> tablebase.close()

• Communicate with UCI/XBoard engines. Based on asyncio. Docs.

  >>> import chess.engine
  
  >>> engine = chess.engine.SimpleEngine.popen_uci("stockfish")
  
  >>> board = chess.Board("1k1r4/pp1b1R2/3q2pp/4p3/2B5/4Q3/PPP2B2/2K5 b - - 0 1")
  >>> limit = chess.engine.Limit(time=2.0)
  >>> engine.play(board, limit)  # doctest:  ELLIPSIS
  <PlayResult at ... (move=d6d1, ponder=c1d1, info={...}, draw_offered=False, resigned=False)>
  
  >>> engine.quit()

If you like, share interesting things you are using python-chess for, for example:

	https://syzygy-tables.info/ A website to probe Syzygy endgame tablebases
	https://maiachess.com/ A human-like neural network chess engine
	clente/chess Oppinionated wrapper to use python-chess from the R programming language
	https://crazyara.org/ Deep learning for Crazyhouse
	http://johncheetham.com A GUI to play against UCI chess engines
	https://pettingzoo.farama.org A multi-agent reinforcement learning environment
	cli-chess A highly customizable way to play chess in your terminal

• extensions to build engines (search and evaluation) – https://github.com/Mk-Chan/python-chess-engine-extensions
• a stand-alone chess computer based on DGT board – http://www.picochess.org/
• a bridge between Lichess API and chess engines – https://github.com/careless25/lichess-bot
• a command-line PGN annotator – https://github.com/rpdelaney/python-chess-annotator
• an HTTP microservice to render board images – https://github.com/niklasf/web-boardimage
• building a toy chess engine with alpha-beta pruning, piece-square tables, and move ordering – https://healeycodes.com/building-my-own-chess-engine/
• a JIT compiled chess engine – https://github.com/SamRagusa/Batch-First
• teaching Cognitive Science – https://jupyter.brynmawr.edu
• an Alexa skill to play blindfold chess – https://github.com/laynr/blindfold-chess
• a chessboard widget for PySide2 – https://github.com/H-a-y-k/hichesslib
• Django Rest Framework API for multiplayer chess – https://github.com/WorkShoft/capablanca-api
• a browser based PGN viewer written in PyScript – https://github.com/nmstoker/ChessMatchViewer
• an accessible chessboard that allows blind and visually impaired players to play chess against Stockfish – https://github.com/blindpandas/chessmart

Thanks to the Stockfish authors and thanks to Sam Tannous for publishing his approach to avoid rotated bitboards with direct lookup (PDF) alongside his GPL2 engine Shatranj. Some move generation ideas are taken from these sources.

Thanks to Ronald de Man for his Syzygy endgame tablebases. The probing code in python-chess is very directly ported from his C probing code.

Thanks to Kristian Glass for transferring the namespace chess on PyPI.

python-chess is licensed under the GPL 3 (or any later version at your option). Check out LICENSE.txt for the full text.