Spring Boot 4 API Starter — Production-Ready REST API (JWT, PostgreSQL, Testcontainers)

Every new API starts the same way: authentication, error handling, migrations, tests, Docker, CI… and the first week is gone before a single business rule is written.

This starter ships all of that done, tested and documented, on the current Spring Boot line (4.1) and Java 21. Download it, run docker compose up, and two minutes later you have a running API with Swagger, users, roles and an example resource ready to copy.

What's included

- Complete auth: register, login, refresh, logout. 15-minute JWT access token + opaque refresh token stored hashed, rotated on every use, with reuse detection.

- USER/ADMIN roles; users only see their own resources.

- PostgreSQL 17 + Flyway migrations, UUID keys, optimistic locking.

- Uniform RFC 9457 errors with stable codes and field errors.

- Pagination, filtering and sorting.

- OpenAPI 3.1 + Swagger UI with Bearer auth pre-configured.

- 30 tests (unit + Testcontainers integration against real PostgreSQL), ~92% line coverage.

- Docker (multi-stage, non-root) + compose.yaml; GitHub Actions CI.

- Scripts: rename the base package in one command, end-to-end smoke test.

- Guides in English and Spanish (Markdown + PDF).

Requirements: JDK 21+ and Docker (Maven Wrapper included).

License: personal license for 1 developer, use and modify in unlimited projects (personal, commercial, client work). Reselling or redistributing the source as a template is not allowed.

Notice: this is a source-code foundation, not a hosted service. Spring, Spring Boot and Java are trademarks of their respective owners; this independent product is not affiliated with or endorsed by Broadcom, VMware or Oracle.