Interoperability in the context of identity wallets and credentials refers to the ability of different systems, platforms, and entities to work together seamlessly to manage, verify, and share digital identities.
The European Digital Identity Wallet Architecture and Reference Framework (ARF) v2.6.0 (13 October 2025) defines the common blueprint for achieving this within the EU, supporting the four Large-Scale Pilots through standardized roles, processes, trust mechanisms, and compliance requirements. The ARF covers the four key interoperability dimensions — Organisational, Legal, Semantic, and Technical, with its strongest emphasis on the Semantic and Technical layers that define data models, attestation formats, and end-to-end presentation flows.
Organisational interoperability aligns goals, workflows, and responsibilities among Wallet Providers, PID Providers, Attestation Providers, Relying Parties, and supervisory actors. The ARF defines these ecosystem roles and their relationships (Chapter 3), ensuring consistent governance and non-discriminatory participation across wallet solutions:
Ecosystem actors and governance:
Defines Wallet Providers, PID and Attestation Providers, Supervisory Bodies, Conformity Assessment Bodies, and Trusted List Providers that coordinate ecosystem oversight (ARF Ch. 3).
Shared processes:
Harmonised lifecycle management — registration, issuance, suspension, revocation — enables coherent workflows across organisations (ARF Ch. 6).
Cross-sector coordination:
While the ARF focuses on EU/EEA contexts, its trust-list model and governance principles support future extensions to non-EU ecosystems (ARF Ch. 6.2–6.3).
Legal interoperability ensures that identity-wallet operations comply with applicable legal and regulatory frameworks, including GDPR and eIDAS 2.0. The ARF embeds compliance and accountability mechanisms through privacy-by-design principles, supervisory structures, and trusted-list-based oversight.
Regulatory compliance:
Applies privacy-by-design, data-minimisation, and selective-disclosure principles consistent with GDPR (ARF Ch. 4.2.4 and Ch. 7).
Cross-border recognition:
Uses EU-wide Trusted Lists and Qualified Electronic Attestations of Attributes (QEAA) to guarantee mutual recognition of credentials (ARF Ch. 6.2–6.3).
Liability frameworks:
Supervisory Bodies and Conformity Assessment Bodies oversee compliance and manage revocation or suspension of actors; accountability derives from Implementing Regulations 2024/2977–2982 (ARF Ch. 3 and 6).
Semantic interoperability guarantees that different systems interpret identity data consistently. This is a core strength of the ARF, which defines common attestation data models, attribute semantics, and catalogues.
Common data models:
Attestation Rulebooks specify the semantics and structure of PID and attribute data using the W3C Verifiable Credentials Data Model and OpenID for Verifiable Credentials (ARF Ch. 5.1–5.4).
Interoperable formats:
Supports JSON-LD, CBOR, and SD-JWT VC formats with machine-readable schemes (ARF Ch. 5.3).
Attribute catalogues and schemas:
Provides catalogues of attributes and attestation schemes for discovery and validation (ARF Ch. 5.5).
Profiles and disclosure policies:
Includes profiles for OpenID4VP (remote presentation) and national implementations with embedded disclosure rules (ARF Ch. 5.6).
Technical interoperability covers the architecture, interfaces, and protocols that allow wallets and relying parties to interact reliably across borders. The ARF defines end-to-end flows for credential issuance, presentation, and trust validation.
Architecture and interfaces:
Describes Wallet Unit components and interfaces (ARF Ch. 4), including remote and proximity presentation flows profiling OpenID4VP and ISO 18013-5 / 23220-2 (ARF Ch. 4.4 and 5.6).
Trust and lifecycle management:
Defines registration, notification, status, and revocation mechanisms for all ecosystem actors (ARF Ch. 6).
Security and compliance:
Sets Wallet Security and Confidentiality requirements and aligns certification with Implementing Regulations 2024/2977–2982 (ARF Ch. 7).
The ARF v2.6.0 most directly enables Semantic and Technical interoperability through its detailed definitions of data models, formats, and protocol flows, while Organisational and Legal aspects are supported via its governance and compliance structures. Together, these elements provide the baseline architecture used by the Large-Scale Pilots to ensure consistent cross-border operation and trust in the European Digital Identity Wallet ecosystem.