OpenScout is a low-cost open source hardware and software mobile robot that can be used for both indoor and outdoor tasks, transporting up to 15 kg of payload. It is designed to be easily and cheaply (350 USD) buildable and modifiable by non-specialists, and to function as a new standard physical platform for robotics research and real-world tasks, replacing current proprietary options. It uses four-wheel differential drive steering, and a hinged body which enables the wheels to drive over small obstacles without the need for suspension. Example applications include last mile and factory floor delivery, site survey and site monitoring.