Assess REST, GraphQL, SOAP, gRPC, and event-driven APIs for OWASP API Security Top 10 risks, authentication and authorization weaknesses, excessive data exposure, schema and input-validation gaps, rate-control issues, and differences between documented and observed behavior. Strong knowledge of REST, GraphQL, API gateways, microservices, HTTP, TLS, JSON, OAuth 2.0, OpenID Connect, JWT, API keys, mutual TLS, service identities, authorization, and common API abuse patterns.