Over the past two decades, open access advocates have made significant gains in securing public access to the formal outputs of scholarly communication (e.g. peer reviewed journal articles) – through a combination of public policy-making, funder mandates and changing the norms and practices of researchers in different fields. The same period has seen the rise of platforms from commercial publishers and technology companies that enable users to interact and share their work, as well as providing analytics and services around scholarly communication. How should researchers and policymakers respond to the rise of these platforms? Do commercial platforms necessarily work the interests of the scholarly community? How and to what extent do these proprietary platforms pose a threat to open scholarly communication? What might public alternatives look like? This paper provides a brief overview of the rise of scholarly platforms – describing some of their main characteristics as well as debates and controversies surrounding them. It argues that in order to prevent new forms of enclosure, it is essential that public policy-makers should be concerned with the provision of public infrastructures for scholarly communication as well as public access to the outputs of research. It concludes with a review of some of the core elements of such infrastructures, as well as recommendations for further work in this area.