This chapter deals with the issue of learning how to improvize. Traditional MOOCs provide jazz students with comprehensive theoretical and motivate students to practice intensively on their own. However, without a view of one's progress, and without feedback, individual practice is a long and winding road along which many students get lost. Indeed, most jazz learning systems lack these two crucial ingredients, resulting in high drop-out rates. This chapter addresses the issue of designing tools for supporting improvisation practice by bringing in a social dimension enabling peer-to-peer feedback, as well as a cloud-based infrastructure enabling arbitrary vizualisations of the evolution of the student performance. We introduce Social Virtual Band, a system that lets learners improvize solos on dynamically created accompaniments, and that records and archives all the training sessions along with the provided accompaniments on the cloud. Simple automatic feedback is presented to measure the evolution of his skills, based on a comparison between played note with scales obtained from automatic harmonic analysis. We describe the overall infrastructure underlying such a tool and discuss how such infrastructure opens up new possibilities for learning music.