Building Secure REST APIs in Spring Boot: Techniques and Tools

Securing REST APIs has become a critical engineering priority as modern applications increasingly rely on distributed microservices and cloud-native architectures. Spring Boot, with its opinionated design philosophy and seamless integration with the Spring Security ecosystem, provides a versatile platform for implementing advanced authentication, authorization, and threat-mitigation strategies. This paper examines the essential security challenges associated with public-facing APIs, including identity verification, token management, transport security, and endpoint hardening. It synthesizes established best practices with emerging techniques such as OAuth2 Resource Servers, JWT-based access control, zero-trust patterns, and API-gateway-augmented threat filtering. Through an in-depth architectural analysis and a practical case study, the work demonstrates how secure design principles can be translated into robust and scalable enterprise-grade API systems. The results highlight measurable improvements in integrity, confidentiality, and resilience under load, offering a reference blueprint for practitioners building secure REST APIs in Spring Boot.