Scid can perform many different searches, such as for particular
players, a certain opening position, material searches, and pattern
searches such as isolated pawns. It is very fast, because it uses its
own efficient format, but it can convert games to and from PGN, the
standard format for chess game files.

Scid can use a chess engine such as Crafty to analyze games and also
has a "tree" mode where it automatically shows all moves played from
the current position, their opening codes, success rates, etc.