The purpose of this article is to investigate the professionalization of activity of those providing services or assets on crowdsourcing platforms. This paper uses a conceptual approach that is rooted in the literature and research on two-sided platforms, shared economy and specific projects such as Airbnb and Uber. On this basis, the professionalisation of crowdsourcing was defined as the process in which individuals who form the crowd providing assets and resources get ultimately transformed into business entities. Furthermore, this paper describes five stages of this process related to the groups of platform users with different degrees of involvement in the provision of services and resources. The approach adopted in this paper makes it possible to take a new look at the dynamic growth of digital platforms, and at the market and social controversies, they excite.