Application Programming Interface Security and Architecture Questions

Design and implementation of secure application programming interfaces and service interfaces, covering architecture, design patterns, and operational controls across monoliths, microservices, and service mesh environments. Topics include authentication and authorization patterns for endpoints such as OAuth two, application programming interface keys, and JavaScript Object Notation Web Tokens; token and key lifecycle and secure storage; mutual Transport Layer Security for service to service authentication; gateway and proxy based controls and hardening; input validation, schema and contract validation, output encoding, parameter filtering, and secure error handling to prevent injection, parameter pollution, and excessive data exposure. Also covers rate limiting, throttling, and anomaly detection to mitigate abuse and credential stuffing; secure transport and encryption in transit and at rest; design of internal versus external trust boundaries; application programming interface discovery and inventory; threat modeling and mitigations for common application programming interface attacks; and operational practices including audit logging, monitoring, alerting, automated security testing, continuous validation, and strategies for scaling security across many endpoints and services.