Using H2 Console with Spring Boot for Debugging

October 15, 2025

This guide shows how to use the H2 console in Spring Boot to debug and inspect database content during development.

1. Add Dependency

In pom.xml:

<dependency>
  <groupId>com.h2database</groupId>
  <artifactId>h2</artifactId>
  <scope>runtime</scope>
</dependency>

2. Enable H2 Console

In application.properties:

spring.datasource.url=jdbc:h2:mem:testdb
spring.datasource.driver-class-name=org.h2.Driver
spring.datasource.username=sa
spring.datasource.password=
spring.jpa.hibernate.ddl-auto=update

spring.h2.console.enabled=true
spring.h2.console.path=/h2-console

Now the console is available at:
http://localhost:8080/h2-console

3. Create a Sample Entity

import jakarta.persistence.*;

@Entity
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String username;
    private String email;
}

4. Repository

import org.springframework.data.jpa.repository.JpaRepository;

public interface UserRepository extends JpaRepository<User, Long> {
}

5. Insert Data and Debug

Add a REST controller to insert users:

import org.springframework.web.bind.annotation.*;
import java.util.List;

@RestController
@RequestMapping("/users")
public class UserController {
    private final UserRepository repo;

    public UserController(UserRepository repo) {
        this.repo = repo;
    }

    @PostMapping
    public User add(@RequestBody User user) {
        return repo.save(user);
    }

    @GetMapping
    public List<User> all() {
        return repo.findAll();
    }
}

6. Test with Console

Start the app:
```
mvn spring-boot:run
```
Open /h2-console.
Use JDBC URL: jdbc:h2:mem:testdb.
Run queries like:
```
SELECT * FROM USER;
```

This helps debug data directly from the DB.