Research Article Under Review Preprint
Currently under journal review. Preprint available (v2, 06 May 2026).
Abstract
Markets for online social networks (e.g., X, Instagram, Linkedin) tend to concentrate, leaving users with little choice: accept the conduct of dominant providers or forgo participation. Digital platform interoperability is widely proposed as a remedy to reduce the economic and political power of centralised platforms by enabling user choice without sacrificing network connectivity. Despite already being included in legal mandates and legislative proposals (e.g., EU Digital Markets Act, US Access Act), interoperability’s effects remain largely untested. This paper empirically evaluates three theoretical expectations about interoperability in social networking platforms. It analyses an original dataset on user switching within the interoperable Mastodon network through a sequential mixed-methods approach. I find evidence that interoperability can expand user choice and identify conditions under which it does so in social networking markets. To neutralise the role of proprietary network effects, interoperability needs to extend beyond ‘tie-based interactions’, familiar from legacy communication networks, to what this paper identifies as ‘open-network interactions’. Interoperability facilitates individual choice and switching, but frictions remain where ‘user assets’ are bundled to ‘provider services’, causing substantial information and switching costs. Contrary to concerns that technical standardisation homogenises services, interoperable providers differentiate vertically (e.g., quality) and horizontally (e.g., governance values), offering meaningful grounds for user choice. This paper’s findings have direct implications for ongoing policy processes and open a research agenda on the dynamics between interoperable but differentiated platform providers.