The Chess Toolkit is a work in progress, but it is quite useful in its current state. It understands the rules of chess, Forsyth-Edwards Notation (FEN), Short Algebraic Notation (SAN), and the basics of Portable Game Notation (PGN). With the current features, you can do a lot. For example, the author has used it to write software that parses through millions of games, collecting statistics on openings and scoring each position based on the game results and player ratings. Hopefully you will find it useful too.