chess.dart is a library for legal chess move generation, maintenance of chess game state, and conversion to and from the formats FEN and PGN. It has no external dependencies.

In 2014, chess.dart started as a port of chess.js to Dart, including all of the functionality in the original library, while making the API a little bit more Dart-like. It has since accumulated bug fixes and performance improvements thanks to contributions from the Dart community.

chess.dart includes a test suite composed of all of the original chess.js unit tests as well as newer tests specific to bug fixes and feature additions specific to the Dart version (which you can find in the test directory). chess.dart is depended upon by multiple popular packages for chess board display.


The package is just called chess on pub. If for some strange reason you can't use pub, you can also just add the chess.dart file from the lib directory to your project. Adding the pub package is:

 $ dart pub add chess

Or you can manually add chess to your pubspec.yaml.

Then importing chess.dart in your code is simply:

import 'package:chess/chess.dart';

A Random Game

import "package:chess/chess.dart";

void main() {
  Chess chess = new Chess();
  while (!chess.game_over) {
    print('position: ' + chess.fen);
    var moves = chess.moves();
    var move = moves[0];
    print('move: ' + move);


The chess.js documentation is largely relevant, but there are also DartDocs generated within the lib/docs directory. The only change in naming from chess.js, is that history() has been changed to getHistory() due to a conflict with the history ivar and some methods have been changed into properties.


chess.dart version 0.6.5 and above requires Dart 2. For Dart 1, use version 0.6.4.


The test directory contains tests.dart which is a port of chess.js's unit tests. The program random.dart plays a random game of chess. ai.dart is an example of a simple 4 ply alpha beta search for black (yes a simple chess-playing program) that uses a purely material evaluation function (it is rather slow). You can run the unit tests using pub:

pub get
pub run test/tests.dart

And you can also run performance tests.

pub run test/perft.dart

And, finally you can run the simple AI:

dart test/ai.dart