Ultimate Spring Boot Interview Questions Guide (Including Spring Security, JPA, and Microservices)

Whether you're prepping for your next Java interview or brushing up on Spring Boot concepts, this all-in-one guide covers everything from fundamentals to real world implementation details.

We've organized questions into Beginner, Intermediate, and Advanced sections for:

• Spring Boot

• Spring Security

• Spring Data JPA

• Microservices

Let’s dive in. 👇

Spring Boot Interview Questions

Beginner-Level

• What is Spring Boot and how is it different from Spring Framework?

• What are the main features of Spring Boot?

• What is the use of @SpringBootApplication annotation?

• What are Spring Boot starters?

• How does Spring Boot help with auto-configuration?

• What is application.properties or application.yml used for?

• How do you run a Spring Boot application?

• What is an embedded server in Spring Boot?

• What is Spring Initializr and how do you use it?

• How do you perform logging in Spring Boot?

Intermediate-Level

• Difference between @Component, @Service, @Repository, and @Controller?

• What is Spring Boot DevTools?

• What is Spring Boot Actuator?

• What is CommandLineRunner and ApplicationRunner?

• How do you connect Spring Boot with databases?

• What is the role of Spring Profiles?

• How do you handle exceptions globally?

• What are custom error pages in Spring Boot?

• How do you validate incoming request bodies using annotations?

• What are beans and how are they managed in Spring Boot?

Advanced-Level

• How does Spring Boot perform auto-configuration internally?

• Explain @ConditionalOnMissingBean, @ConditionalOnProperty, etc.

• How do you configure and customize the embedded Tomcat server?

• What happens in the background during Spring Boot app startup?

• How does Spring Boot load properties from multiple sources?

• How do you build and deploy a Spring Boot app with Docker?

• How do you implement caching in Spring Boot?

• How do you write integration tests in Spring Boot?

• Explain the use of externalized configuration with Spring Cloud Config.

• How do you implement pagination and sorting with Spring Data?

Spring Security Interview Questions

Beginner-Level

• What is Spring Security and why is it used?

• How does Spring Security handle authentication and authorization?

• What is a security filter chain?

• What is CSRF and how does Spring Security handle it?

• How do you secure a REST API with Spring Security?

Intermediate-Level

• How do you implement role-based access control?

• How do you secure endpoints with method-level annotations?

• How do you store and validate user credentials in Spring Security?

• What is the difference between UserDetailsService and AuthenticationProvider?

• What are GrantedAuthority and SimpleGrantedAuthority?

Advanced-Level

• How do you secure REST APIs using JWT in Spring Boot?

• How do you integrate OAuth2/OpenID Connect in Spring Security?

• How do you configure a custom security filter?

• How does Spring Security handle session management?

• How do you implement multi-factor authentication?

Spring Data JPA Interview Questions

Beginner-Level

• What is JPA and how does it relate to Hibernate?

• What is Spring Data JPA?

• How do you define a JPA repository?

• What are entities in JPA?

• What is the use of @Id and @GeneratedValue?

Intermediate-Level

• How do you create custom queries with @Query?

• What is the difference between findById() and getOne()?

• What is lazy loading vs. eager loading?

• How do you handle transactions in JPA?

• What are cascading types?

Advanced-Level

• How do you write specifications with the JPA Criteria API?

• What is the N+1 query problem and how do you resolve it?

• How do you implement auditing in JPA?

• How does Spring Data JPA generate query implementations?

• How do you map relationships: OneToMany, ManyToOne, etc.?

Microservices Interview Questions

Beginner-Level

• What are Microservices?

• How do Microservices differ from Monolithic architecture?

• What are the key benefits of Microservices?

• What is a service registry?

• What is service discovery?

Intermediate-Level

• What is Spring Cloud and how does it support Microservices?

• How do Microservices communicate with each other?

• What is an API Gateway?

• What is Circuit Breaker pattern? How is it implemented?

• What are common challenges with Microservices?

Advanced-Level

• How do you handle distributed transactions?

• How do you ensure data consistency in a microservices architecture?

• What is eventual consistency?

• How do you implement centralized logging?

• How do you secure Microservices communication?

• How do you implement versioning in Microservices?

This list is a comprehensive guide for interview prep and real-world reference. Whether you're applying for a Java backend role or building your next scalable app, mastering these concepts is key to working with Spring-based systems.

Tips:

• Practice hands-on projects to reinforce theory.

• Explore Spring Docs and official guides.

• Stay updated with the latest Spring Boot, Spring Security, and Spring Cloud releases.