i-Sprint AccessMatrix Universal Authentication Server (UAS) is a vendor-agnostic authentication platform designed to consolidate multiple authentication methods, token providers, biometric systems, and Hardware Security Modules (HSMs) under a single unified architecture. The platform uses a pluggable, modular design that allows IT teams to add, update, or replace authentication methods — such as passwords, OTPs, and FIDO2 — without rewriting existing application integrations. Each authentication type is managed through its own module, meaning applications are abstracted from the underlying token or biometric specifics. UAS supports a range of biometric modalities including face, fingerprint, iris, voice, and palm vein recognition. It includes built-in FIDO2 device lifecycle management covering registration, verification, and ongoing management. For cryptographic operations, the platform integrates with multiple HSM providers to avoid hardware vendor lock-in. It also includes AI-driven adaptive authentication that evaluates real-time signals such as device reputation, location, time of access, and usage patterns to dynamically adjust authentication requirements. The system is designed for high-volume deployments and has been tested to support over 100 million users, targeting use cases in government, financial services, and large-scale consumer applications. UAS is built with Post-Quantum Cryptography (PQC) readiness in mind, employing a modular cryptographic architecture that allows new PQC algorithms to be introduced as they are standardized.