Spring Boot 4 REST API from Scratch — H2, JPA, MapStruct & Lombok

In this video we build a full CRUD REST API using Spring Boot 4. We set up an H2 in-memory database, define JPA entities, use Lombok to eliminate boilerplate, and wire everything together with MapStruct DTOs. By the end you'll have a working /users API you can test with curl or Postman.