How to Solve Real-Time Auth Without Having to Sacrifice Performance

Modern web applications face a major challenge when securing real-time WebSocket connections with external authentication providers like Keycloak, as traditional token introspection creates performance bottlenecks. This guide demonstrates building a high-performance WebSocket server in Symfony that validates Keycloak JWTs locally using cryptographic signature verification instead of slow API calls. The solution caches Keycloak's public keys and performs Just-in-Time user provisioning, eliminating authentication delays while maintaining enterprise-grade security.