This paper presents the findings of an international and interdisciplinary review of the literature on digital platforms and cities, with a focus on sharing (peer-to-peer) and forprofit (monetary exchange) platforms. First, the paper discusses why the development of virtually mediated peer-to-peer exchanges is a significant facet of contemporary urban change. Second, it develops a literature review clustered around five main empirical questions that may be relevant to urban research (the nature and boundaries of platform-mediated exchanges; their size and socio-economic organisation; their income and spatial distributional effects; their effects on existing markets; and their regulation and governance). This reveals that virtually mediated P2P exchanges have so far been addressed as a phenomenon sui generis. As discussed in the concluding section, urban research now needs to consider them within their broader urban contexts and in the light of sociological and political urban theory, in order to understand the mechanisms through which they interact with ongoing processes of social, spatial, economic and political restructuring of cities.