Open, Reusable Digital Solutions: Building Blocks for a Connected Europe

The concept of building blocks/open digital solutions for achieving interoperability, enables modular components of infrastructure or software solutions to be combined and interconnected in order to achieve interoperability between different systems or applications.

Based on standards that can be reused, building blocks/open digital solutions provide essential capabilities, such as reliable authentication and secure data exchange, which can be used in any European project to facilitate the provision of cross-border digital public services. By relying on standard interfaces, protocols, or technologies, they ensure compatibility and seamless communication between different systems.

The use of building blocks/open digital solutions offers significant benefits. Organizations can build or expand their systems using existing components that have already proven their interoperability. They also facilitate faster and more cost-effective development cycles, as teams can focus on adding new functionalities instead of reinventing entire systems.

Initially supported through the Connecting Europe Facility (CEF) (2014-2020), and now through the more ambitious Digital Europe Programme (DIGITAL) (2021-2027), this approach helps public administrations and businesses avoid "vendor lock-in," where they become dependent on a single technological solution, and foster a more competitive and innovative market. This philosophy of reuse has become a fundamental tool for achieving the broader goal of European "digital sovereignty," reducing dependence on technologies from third countries and strengthening the Union's ability to make independent decisions in the digital domain.

Examples of such blocks may include web services, APIs (Application Programming Interfaces), standardized data formats, or software libraries that facilitate data exchange and integration.

Existing Digital Building Blocks for Europe include eDelivery, eID, eInvoicing, eSignature, the Once-Only Technical System (OOTS), EUDI and EBSI.

As the European Union transitions from a period of developing individual solutions and frameworks to implementing a more cohesive, legally-backed approach to interoperability across the Union, the Interoperable Europe Act holds a key role. IEA introduces mandatory mechanisms such as interoperability assessments before the introduction of new IT systems, mandatory sharing of solutions via the Interoperable Europe Portal and, establishes a formal governance structure, the Interoperable Europe Board, composed of representatives from the Member States and the Commission. Furthermore, the IEA promotes innovation through regulatory sandboxes, enabling public and private organizations to collaboratively test new solutions.

In this evolving landscape, the INVEST project plays a critical role in enhancing the interoperability of digital public services across Europe. It builds on the framework established by the IEA as well as on existing, proven solutions like the EU-level building blocks. INVEST also seeks to identify potential synergies between different EU initiatives and national programs. 

Through extensive mapping of existing solutions, gap analysis, and promoting collaboration, INVEST supports the practical implementation of interoperability policies.

As part of its work, INVEST conducted an EU-wide desk research to provide a comprehensive analysis of the current landscape of interoperability solutions in relation to the requirements set by the Interoperable Europe Act. Its objectives were twofold: first, to uncover national solutions and reusable tools that enhance cross-border interoperability; and second, to gain insights into how existing EU-level solutions are integrated and utilized.

Key Findings

The research revealed that while Member States actively incorporate EU-level building blocks into their national digitalization strategies, official documentation and communication often focus on the final digital services rather than on the underlying interoperability mechanisms. This makes it challenging to fully understand how interoperability is operationalized at the national level; while EU-level solutions are well-documented with clear technical specifications and interoperability frameworks, national implementations often lack transparent documentation of how these building blocks are integrated, adapted, and extended within national contexts.

Nevertheless, as a result of the research, it was evident that the CEF Building Blocks and certain components from eu-LISA systems are widely used to support cross-border services, especially in domains where EU regulations mandate cooperation (such as transport, border control, and defense).

Reusable digital building blocks/open digital solutions are at the heart of Europe's strategy to achieve digital sovereignty and seamless cross-border digital services. Through legislative measures like the Interoperable Europe Act and initiatives like INVEST, the EU is creating a robust framework that encourages openness, reduces dependency, and drives innovation across Member States.