Features:

Openpilot is a next-generation Open Source UAV autopilot. 
It is a highly capable platform for multirotor craft, helicopter, as well as fixed wing aircraft. 
Simplicity does not come with any compromises either: with no hard-coded settings, a complete flight plan scripting language and other powerful features, Openpilot is an extremely capable UAV autopilot platform.
Powerful STM32 32-bit microcontroller running at 90MIPs with 128KB Flash and 20KB RAM.
3-axis high-performance MEMs gyros and 3-axis high-performance MEMs accelerometer.

Openpilot CC3D Flight Controller vertical or side pin versions available
All-in-one stabilization hardware which runs the OpenPilot firmware
Openpilot CC3D Open Source Flight Controller 32 Bits Processor for QAV250 FPV Quadcopter
Tiny 36mm*36mm 4 layer PCB for superior electrical noise reduction and flight performance
It has been designed from the ground up by a community of passionate develope from around the globe, with its core design principals being quality, safety, and ease of use