This repository is a sample Spring Boot application that demonstrates custom JWT token-based authentication for protecting RESTful APIs. It provides a vehicle CRUD API (via both a custom controller and Spring Data REST), a user authentication endpoint (/auth/signin), and a user info endpoint (/me). The architecture follows a standard Spring Boot monolith with Spring Security, Spring Data JPA, and Spring HATEOAS. The custom JWT implementation is encapsulated in a JwtTokenProvider and a JwtTokenAuthenticationFilter, which extract, validate, and set authentication from JWTs. The codebase is modern, using Spring Boot 3.x, Jakarta EE, Java 21, and the latest JJWT library. It includes unit tests, integration tests, and a docker-compose file for PostgreSQL. While the core functionality is straightforward and typical for such samples, the separation of JWT logic into reusable components and the use of Spring Boot 3.x best practices make it a solid reference implementation. It is primarily an application with no data research elements.