Top Springboot Interview Questions (2025)

Spring Boot is a popular Java framework that simplifies the process of building stand-alone, production-grade applications. As a result, it has become a highly in demand skill in the industry, and many companies are looking for developers who are proficient in Spring Boot.

In this article, we will cover some of the most common Spring Boot interview questions, along with their answers.

Core Spring Boot Questions

1. What is Spring Boot?

Spring Boot is an extension of the Spring Framework that simplifies the process of building stand-alone, production-grade applications.

2. What are the key features of Spring Boot?

Auto-configuration
Embedded Tomcat or Jetty server
Simplified dependency management
Automatic configuration of Spring and third-party libraries

3. How does Spring Boot handle auto-configuration?

Spring Boot uses a combination of Java-based configuration and annotation-based configuration to automatically configure the application. It also uses a concept called “starter” dependencies to simplify the process.

4. What is the difference between @SpringBootApplication and @EnableAutoConfiguration?

@SpringBootApplication annotation that enables auto-configuration, component scanning, and other features. @EnableAutoConfiguration annotation that only enables auto-configuration.

5. How do you configure a data source in Spring Boot?

You can configure a data source in Spring Boot using application.properties or application.yml files. For example:

application.properties –

spring.datasource.url=jdbc:mysql://localhost:3306/mydb
spring.datasource.username=myuser
spring.datasource.password=mypassword

Spring Boot and Database Questions

6. What is the difference between @Repository and @Dao?

@Repository and @Dao are used to indicate that a class is a (data access object) DAO, @Repository is a Spring-specific annotation that provides additional features and integration with the Spring Framework, whereas @Dao is a more general-purpose annotation that can be used in any Java application.

7. How do you use Spring Data JPA in a Spring Boot application?

You can use Spring Data JPA in a Spring Boot application by adding the spring-boot-starter-data-jpa dependency to your pom.xml file and creating a repository interface that extends JpaRepository.

8. What is the difference between Hibernate and Spring Data JPA?

Hibernate is an ORM (Object-Relational Mapping) tool that maps Java classes to database tables. Spring Data JPA is a higher-level abstraction that provides a simpler way to interact with databases using Hibernate or other ORM tools.

Spring Boot and Deployment Questions

9. How do you deploy a Spring Boot application to a Docker container?

You can deploy a Spring Boot application to a Docker container by creating a Dockerfile, building a Docker image, and then running the image as a container.

10. What is the difference between embedding Tomcat and using an external Tomcat server in a Spring Boot application?

Embedding Tomcat is suitable for smaller-scale applications that require simplified deployment and management. Using an external Tomcat server is more suitable for larger-scale applications that require scalability, flexibility, and better resource management. Ultimately, the choice between embedding Tomcat and using an external Tomcat server depends on the specific needs and requirements of your Spring Boot application.

Spring Boot and Security Questions

11. What is Spring Security?

Spring Security is a framework that provides authentication and authorization for Spring-based applications.

12. How do you configure Spring Security in a Spring Boot application?

You can configure Spring Security in a Spring Boot application using the spring-boot-starter-security dependency and creating a configuration class that extends WebSecurityConfigurerAdapter.

13. What is the difference between authentication and authorization?

Authentication is the process of verifying the identity of a user. Authorization is the process of determining what actions that user can perform.

14. How do you implement authentication and authorization in a Spring Boot application using Spring Security?

You can implement authentication and authorization in a Spring Boot application using Spring Security by configuring the security settings in the application.properties or application.yml files and creating a security configuration class.

15. What is the difference between @Secured and @PreAuthorize annotations in Spring Security?

@Secured is used to enable security for a method or class, while @PreAuthorize is used to specify the security roles that are required to access a method or class.

Spring Boot and Testing Questions

16. What is the purpose of the @SpringBootTest annotation?

The @SpringBootTest annotation is used to enable Spring Boot features in a test class.

17. How do you write unit tests for a Spring Boot application?

You can write unit tests for a Spring Boot application using JUnit or TestNG. You can also use mocking frameworks like Mockito to isolate dependencies.

18. What is the difference between @MockBean and @Mock?

@MockBean is a Spring Boot annotation that creates a mock bean in the application context. @Mock is a Mockito annotation that creates a mock object.

19. What is the difference between @SpringBootTest and @WebMvcTest annotations in a Spring Boot test class?

@SpringBootTest is used to enable Spring Boot features in a test class, while @WebMvcTest is used to enable Spring MVC features in a test class.

Spring Boot and Microservices Questions

20. How do you implement load balancing in a Spring Boot microservices-based system?

Implementing load balancing in a Spring Boot microservices-based system can be achieved using various approaches, including client-side load balancing with Ribbon, server-side load balancing with Netflix Zuul, and using Spring Cloud LoadBalancer. Each approach has its own advantages and disadvantages, and the choice of approach depends on the specific requirements of the system.

21. What is the purpose of the @EnableDiscoveryClient annotation in a Spring Boot application?

The @EnableDiscoveryClient annotation is used in a Spring Boot application to enable the DiscoveryClient feature, which allows the application to register itself with a service registry and discover other services.

Spring Boot and Performance Questions

22. How do you optimize the performance of a Spring Boot application?

You can optimize the performance of a Spring Boot application by using caching, optimizing database queries, and configuring the JVM for optimal performance.