✔Spring Security 6 with OAuth 2.0 and JWT: short-lived tokens, refresh rotation, and scope-based method-level security from the first commit.
✔Versioned REST design: URL versioning with backward-compatibility contracts so existing consumers keep working.
✔OpenAPI 3 with SpringDoc: machine-generated documentation from code annotations - always accurate, never stale.
✔Spring WebFlux: reactive, non-blocking APIs for endpoints handling thousands of concurrent connections.
✔API Gateway with rate limiting: per-consumer limits, request validation, and IP allowlisting for B2B APIs.
✔Micrometer observability: request count, error rate, and P50/P95/P99 latency published from day one.