interID -- An Ecosystem-agnostic Verifier Application for Self-sovereign Identity

Self-Sovereign Identity is a transformative paradigm in digital identity management, empowering individuals with full control over their credentials. However, the coexistence of diverse SSI ecosystems, such as the European Digital Identity and the European Blockchain Services Infrastructure, poses significant challenges for cross-ecosystem interoperability due to technological and trust framework differences. This paper introduces \textit{interID}, a modular credential verification application that addresses this fragmentation by orchestrating ecosystem-specific verifier services. Our key contributions include: (1) an ecosystem-agnostic orchestration layer that interfaces with multiple SSI verification services, (2) a unified API that abstracts underlying protocol complexities for service providers, and (3) a practical implementation that bridges three major SSI ecosystems: Hyperledger Indy/Aries, EBSI, and EUDI. Evaluation results demonstrate that interID successfully verifies credentials across all tested wallets with minimal performance overhead, while maintaining a flexible architecture that can be extended to accept credentials from additional SSI ecosystems. This work offers both a technical solution and architectural pattern for achieving interoperability in SSI verifier implementations.