Service-to-Client Interoperability as a Consumer Protection Measure

Submitted as an appendix to the European Commission's Digital Fairness Act consultation, this briefing distinguishes "service-to-client" interoperability, letting a user's preferred third-party client or tool talk to a platform's existing backend, from the more complex "service-to-service" interoperability that Article 7 of the Digital Markets Act already mandates for messaging apps. It argues the former is simpler, lower-risk and, in most cases, already technically present, just restricted to first-party clients the service provider itself controls.

Drawing on existing third-party tools such as spam- and troll-detection add-ons, browser extensions that restore old verification badges or crowd-source video quality signals, community-moderation tooling used by Reddit moderators, and price-history and review-trust tools for online marketplaces, the brief shows that service-to-client interoperability already lets users regain a degree of autonomy over their feeds, moderation and purchasing decisions when platforms allow it.

Its core recommendation is that the Digital Fairness Act mandate this kind of interoperability as a baseline consumer protection, since it requires platforms only to document interfaces that already exist internally rather than build new infrastructure, framing it as a return to a more open internet rather than a novel intervention.