Online platforms facilitate market entry for firms by providing an online presence and by giving access to clients and market information. Especially for smaller and medium-sized enterprises (SME) they provide capacities to compensate insufficient funds and technical skills.However, the proportion of businesses already exploiting these advantages of the digital economy has been growing only slowly. Especially SMEs seem reluctant to make use of the new opportunities. The causes for the limited use are likely to be manifold and complex. Some of the reasons may relate to the contractual design and practices of B2B relations between the online platforms and their business users.The objective of this project is to provide additional evidence on the actual scope and scale and impact of potentially unfair B2B trading practices applied by online platforms, beyond the application of competition law. To this end, the study will identify and assess potentially problematic B2B practices of major online platforms, especially in relation to SMEs. The experiences of business users of online platforms and of the platforms themselves will be the central focus of research. The study will also map out relevant redress possibilities currently offered.