Open pilot: this is an autopilot that has been created by a community that belongs to a group of volunteers and is non-profit. This community is known as open pilot. This software is designed especially for the rotor system that contains more than one rotor. The only concern of the developers is to give to the client quality, safety and an easy to use UAV.
Paparazzi: this hardware plus software combo is a great open source autopilot system that is aimed at being used for fixed wing aircraft and the UAVs. Since this is open source software anyone can add or make any kind of changes to suit their needs. It is because of the volunteers that this system is getting better day by day.