ABSTRACT What do platforms owe their users, and what do users owe platforms? We adapt the concept of asymmetrical reciprocity from political anthropology as a framework for critiquing the moral economies of platform power. Asymmetrical reciprocities are collectively held beliefs that authority figures should give or receive more than is normally acceptable. We argue that platforms style themselves as patrons to legitimize their asymmetric power – they cultivate a perception of giving more than they take so that, in practice, they can take more than they give. This is a fragile legitimacy, however, and users are not dupes. Users push back against policies that benefit platforms at their expense by issuing demands and coordinating action. We present three vignettes showing this process among a diverse set of platform constituencies – live-streamers, e-book authors, and sex workers. The vignettes show how asymmetrical reciprocities generate frictions that can destabilize platform legitimacy. Finally, we argue that where platforms choose to invest in ‘legitimacy costs’ reveals the asymmetricality of platform power. Platforms grant inducements and concessions for privileged users, but subject marginalized groups to a coercive regime of policing and exclusion.