Mechanised grading is now mature. In this paper, we propose elements for the next step: building a commodity infrastructure for grading. We propose --- an architecture for a grading component able to be embedded into various learning environments, --- a set of extensible Internet-based protocols to interact with this component, and --- a self-contained file format to thoroughly define an exercise in order to ease deployment. The infrastructure was designed to be scalable, robust and secure. First experiments with a partial implementation of this platform show the versatility and the neutrality of the grading component. It does not impose any IDE and it respects the tenets of the embedding learning environment or course-based system.