方蟹科（Grapsidae）是十足目短尾下目（螃蟹）的其中一个科。他们主要生活在沼泽和近岸的地方，以海藻等为食。

方蟹科过往分成多个亚科，但这些亚科现时均已独立出来成为一个科，再组成方蟹总科。 虽然如此，现时动物学家仍未能肯定方蟹科是否一个单系群。现时方蟹科还有以下十个属，包括两个只余下化石的已灭绝的属：

Grapsidae is a family of crabs known variously as marsh crabs, shore crabs or talon crabs. It is not confirmed that the family forms a monophyletic group and some taxa may belong in other families. They are found along the shore among rocks, in estuaries, marshes, and in some cases pelagic among drifting seaweeds and flotsam.