UTA is an open-source trust interoperability layer for AI agents. It translates between 8 credential formats — including ATC, EAT-AI, ZTA, A2A, MCP, W3C VC, OAuth, and SPIFFE — through a canonical Universal Trust Schema. It provides a 12-stage fail-closed verification pipeline with Ed25519 signatures and RFC 8785 JCS canonicalization, making trust verification portable across agent ecosystems.