A fan blade platform seal includes a platform portion including a first side and a second side opposite the first side. The platform portion further includes a flow path surface extending between the first side and the second side and a bonding surface opposite the flow path surface. The fan blade platform seal further includes a first seal portion including a first bonding segment including a first outer surface, mounted to the platform portion on the first side of the platform portion, and a first inner surface opposite the first outer surface. The fan blade platform seal further includes a stiffening portion mounted to the first inner surface. The stiffening portion includes a first bonding layer bonded to the first inner surface and a stiffening layer bonded to the first bonding layer on a first layer side of the stiffening layer.