Advancing interoperability of data exchange in Europe: Insights from Estonia’s experience for the common European data spaces

Interoperability is one of the most critical enablers for the success of the Common European Data Spaces (CEDS). The entry into force of the Interoperable Europe Act in April 2024 marked a pivotal moment in formalising a legal framework to support this vision. Among the emerging data spaces, the European Data Space for Smart Communities (DS4SSCC) has attracted particular attention for its ambition to act as a "connector data space," linking stakeholders, platforms, and technologies across local, regional, and national levels, as well as domains, with a focus on community-level challenges and needs. This paper offers a novel contribution by bridging real-world national and cross-border interoperability practices - particularly Estonia's operational experience with X-Road - with the strategic development of European-level data space initiatives. Unlike prior studies that focus predominantly on technical frameworks or high-level policy design, this paper provides grounded, practical insights from Estonia's long-standing implementation and institutionalisation of data exchange interoperability, translating them into actionable recommendations for DS4SSCC and other CEDS. We argue that the primary obstacles to data exchange interoperability are typically associated with organisational, political, and legal aspects, rather than purely technological ones. Accordingly, effective data governance, stakeholder coordination, and regulatory alignment are essential. To contextualise Estonia's experience, the paper incorporates a comparative analysis of other key European data space initiatives. This broader perspective situates Estonia's X-Road model within a diverse ecosystem of approaches, enriching the relevance and applicability of the findings to DS4SSCC and other CEDS. We provide recommendations across three pillars: (1) clear incentives and legal alignment; (2) sustainable organisational structures; and (3) demonstrable value for stakeholders. These aim to guide the DS4SSCC and other CEDS toward becoming scalable, trusted, and inclusive parts of the European data ecosystem.