Landing your dream Java developer job starts with mastering Spring Boot interview questions. Many developers feel worried as interview day approaches, but you can walk in with confidence!
This guide breaks down exactly what hiring managers want to hear when they ask about Spring Boot. We’ve gathered the top 15 questions that appear in real interviews, along with expert-tested answers that showcase your skills.
Ready to impress your next interviewer? Let’s turn those interview jitters into your secret weapon for success.
Spring Boot Interview Questions & Answers
These questions reflect what technical interviewers are asking right now. Each answer is crafted to help you stand out as a candidate.
1. What is Spring Boot and how does it differ from traditional Spring Framework?
Employers ask this question to gauge your foundational understanding of Spring Boot and its value proposition. This helps them determine if you grasp the core concepts that make Spring Boot different from other frameworks. They want to see that you understand why companies choose Spring Boot for their projects.
The main difference lies in Spring Boot’s opinionated approach to configuration. While traditional Spring requires extensive XML or Java-based configuration, Spring Boot uses sensible defaults and auto-configuration to eliminate much of that boilerplate code. This means you can set up applications faster and focus on business logic rather than infrastructure setup.
With Spring Boot, you also get embedded servers, health checks, and metrics built-in, making deployment simpler than with traditional Spring applications. The starter dependencies bundle compatible libraries together, solving version conflicts automatically and speeding up your development process significantly.
Sample Answer: Spring Boot is an extension of the Spring Framework that simplifies Java application development by reducing configuration overhead. Unlike traditional Spring, which requires extensive manual configuration, Spring Boot uses an opinionated approach with auto-configuration, embedded servers, and starter dependencies. For example, instead of manually configuring a database connection in Spring, Boot automatically configures it based on dependencies in your classpath. This means I can create production-ready applications much faster, focusing on business logic rather than infrastructure setup.
2. Explain Spring Boot auto-configuration. How can you disable specific auto-configuration classes?
Interviewers ask this to verify your hands-on experience with Spring Boot’s core functionality. Understanding auto-configuration shows you can work effectively with the framework and troubleshoot issues when default behaviors don’t match project requirements. This knowledge is crucial for any Spring Boot developer.
Auto-configuration works by examining your application’s classpath, dependencies, and existing beans to automatically configure components you’re likely to need. For instance, if Spring Boot detects H2 database on your classpath, it will automatically configure an in-memory database without requiring explicit configuration from you.
To disable specific auto-configuration classes, you can use the exclude attribute in the @SpringBootApplication annotation or in your application.properties file. This gives you precise control over which automatic configurations take effect, allowing you to customize behavior while still benefiting from automatic setup for other components.
Sample Answer: Auto-configuration is Spring Boot’s magic that automatically configures your application based on the dependencies you’ve added to your project. It works through conditional annotations like @ConditionalOnClass and @ConditionalOnMissingBean that evaluate your classpath and existing beans. To disable specific auto-configurations, I typically use the exclude parameter in the @SpringBootApplication annotation like: @SpringBootApplication(exclude = {DataSourceAutoConfiguration.class}). Alternatively, I can use the spring.autoconfigure.exclude property in application.properties. I’ve used this approach when implementing custom security configurations that would conflict with Spring Boot’s defaults.
3. What are Spring Boot Starters? Name some commonly used starters.
Hiring managers ask this question to assess your familiarity with Spring Boot’s component ecosystem. Knowledge of various starters demonstrates that you can efficiently set up different types of applications without reinventing the wheel. This practical knowledge signals that you’ll be productive quickly.
Spring Boot Starters are dependency descriptors that bundle compatible versions of commonly used libraries for specific functionality. They solve the problem of dependency management by providing pre-configured dependencies that work well together. This eliminates version conflicts and reduces the time spent researching compatible library versions.
Each starter serves a particular purpose – from web applications to data access, security, or messaging. For example, spring-boot-starter-web includes everything needed for building web applications, including Spring MVC and embedded Tomcat. This modular approach lets you add exactly what your application needs without unnecessary bloat.
Sample Answer: Spring Boot Starters are curated sets of dependencies that simplify project setup by bundling compatible libraries for specific functions. They follow a naming convention: spring-boot-starter-X. Some commonly used starters include spring-boot-starter-web for web applications with Spring MVC, spring-boot-starter-data-jpa for database access using JPA, spring-boot-starter-security for authentication and authorization, spring-boot-starter-test for testing support, and spring-boot-starter-actuator for monitoring and management. When building a REST API recently, I used spring-boot-starter-web and spring-boot-starter-validation together, which gave me everything I needed for input validation and HTTP request handling without hunting for compatible libraries.
4. How do you create a Spring Boot application? Explain the steps.
This question helps employers assess your practical knowledge of setting up Spring Boot projects from scratch. It reveals whether you can independently create applications or if you’ll need extensive guidance. Your answer shows your familiarity with the development workflow.
The first step involves using either Spring Initializer (start.spring.io), Spring Boot CLI, or an IDE like IntelliJ or Eclipse with Spring Boot plugins. These tools create the basic project structure with the correct Maven/Gradle configuration and essential dependencies. You’ll select your project metadata, dependencies, and Java version.
After generating the project, you’ll implement your business logic by creating components like controllers, services, and repositories. Then you’ll configure application properties if needed, though Spring Boot’s defaults often work well out of the box. Finally, you build and run the application using the embedded server that comes with Spring Boot, making the development-to-deployment cycle much faster.
Sample Answer: I create Spring Boot applications in four main steps. First, I generate the project structure using Spring Initializer (start.spring.io), selecting my preferred build tool, Java version, and dependencies. Second, I import the project into my IDE and review the generated files, particularly the main application class with @SpringBootApplication annotation. Third, I implement my business logic by creating packages for controllers, services, repositories, and models, adding the necessary code and annotations. Finally, I configure application-specific properties in application.properties or application.yml and run the application using the main class or Maven/Gradle commands. This approach ensures a clean, organized project structure from the start.
5. What is Spring Boot Actuator? How is it useful?
Employers ask this to determine if you understand production-ready features that go beyond basic application development. Knowledge of Actuator indicates you consider operational aspects like monitoring and maintenance, which is valuable for enterprise applications. It shows you think about the full application lifecycle.
Spring Boot Actuator adds production-ready features to your application with minimal setup. It provides HTTP endpoints or JMX beans that expose operational information about your running application. This includes health checks, metrics, environment information, and more that help operations teams monitor and manage applications effectively.
Actuator becomes especially valuable in microservices environments where you need to track the health and performance of multiple services. You can customize the security of these endpoints and even extend Actuator with your own metrics and health indicators. This makes troubleshooting easier and provides valuable insights without building custom monitoring solutions.
Sample Answer: Spring Boot Actuator is a sub-project that adds production-ready features to applications with minimal code. It provides HTTP endpoints that expose operational data like health status, metrics, environment details, and logging information. In my last project, I used Actuator’s /health endpoint to integrate with our monitoring system to track application status, and /metrics to collect performance data. I also customized health indicators to check critical dependencies like database connections and message queues. The /env endpoint proved invaluable for troubleshooting configuration issues across different environments. Actuator saved us from building custom monitoring code while giving us comprehensive visibility into our application’s operational state.
6. What is the significance of @SpringBootApplication annotation?
Interviewers ask this to check your understanding of Spring Boot’s core annotations and configuration approach. This knowledge shows you grasp how Spring Boot streamlines the development process. Understanding this annotation demonstrates your ability to configure Spring Boot applications correctly.
The @SpringBootApplication annotation serves as a convenience annotation that combines three other annotations: @Configuration, @EnableAutoConfiguration, and @ComponentScan. This single annotation triggers Spring Boot’s auto-configuration mechanism, component scanning, and bean registration, saving you from adding multiple annotations separately.
When you use @SpringBootApplication, Spring Boot automatically searches for components in the package containing your main class and all sub-packages. It also enables auto-configuration based on your classpath. This powerful combination is why Spring Boot applications require so little boilerplate code compared to traditional Spring applications.
Sample Answer: @SpringBootApplication is a compound annotation that combines three essential annotations: @Configuration (designates the class as a source of bean definitions), @EnableAutoConfiguration (enables Spring Boot’s auto-configuration mechanism), and @ComponentScan (scans for Spring components in the package and sub-packages). When I place this on my main class, it eliminates the need for separate XML configuration while automatically setting up the application context. In a recent microservice project, this allowed me to have minimal configuration while still leveraging Spring’s powerful dependency injection and component management. The class with this annotation typically contains the main() method that launches the application using SpringApplication.run().
7. How can you configure properties in Spring Boot?
Employers ask this question to evaluate your knowledge of application configuration options in Spring Boot. It shows whether you can adapt applications to different environments and requirements without code changes. This practical skill is essential for real-world development work.
Spring Boot offers multiple ways to configure your application, with a clear order of precedence. The most common approach is using application.properties or application.yml files in the src/main/resources directory. These files contain key-value pairs that Spring Boot automatically loads at startup.
For environment-specific configurations, you can create profile-specific property files like application-dev.properties or application-prod.yml. You can also override properties using command-line arguments, environment variables, or even through cloud configuration servers for distributed systems. This flexibility allows you to deploy the same application with different configurations across environments.
Sample Answer: In Spring Boot, I configure properties through several methods depending on the situation. My primary approach is using application.properties or application.yml files in the resources directory for default settings. For environment-specific configs, I create files like application-dev.yml and application-prod.yml and activate them with spring.profiles.active. When working with sensitive information like database credentials, I use environment variables or command-line arguments that override file-based properties. For complex configurations, I organize properties into @ConfigurationProperties classes with proper validation. This layered approach gives me flexibility while maintaining security and clarity in configuration management.
8. How do you handle exceptions in a Spring Boot REST application?
This question helps interviewers assess your ability to build robust applications that gracefully handle errors. Good exception handling is crucial for maintaining API contracts and providing meaningful feedback to clients. It demonstrates your attention to quality and user experience.
The most effective approach is using Spring’s @ControllerAdvice and @ExceptionHandler annotations to create global exception handlers. This centralized approach lets you consistently transform exceptions into appropriate HTTP responses across your entire application, ensuring a uniform error handling strategy.
You should also create custom exception classes for business-specific errors, map them to appropriate HTTP status codes, and return structured error responses with meaningful messages. This makes your API more developer-friendly and easier to consume. Additionally, you can log exceptions for troubleshooting while still presenting clean, sanitized error messages to end users.
Sample Answer: I handle exceptions in Spring Boot REST applications using a layered approach. First, I create custom exception classes for different error scenarios (like ResourceNotFoundException, ValidationException). Then, I implement a global exception handler with @ControllerAdvice and @ExceptionHandler annotations that converts these exceptions into appropriate HTTP responses. For example, my handler maps ResourceNotFoundException to a 404 status and ValidationException to a 400 status. I structure error responses consistently with fields like status, message, and timestamp. For validation errors, I include field-level details. I also use Spring’s ResponseStatusException for simple cases. This approach centralizes error handling logic, maintains consistent error formats, and makes debugging easier while keeping controllers clean.
9. What is Spring Boot DevTools? How does it improve developer productivity?
Interviewers ask this to gauge your familiarity with development acceleration tools in the Spring ecosystem. Knowledge of DevTools indicates you value efficiency and know how to speed up the development cycle. This can make you more productive as a team member.
Spring Boot DevTools is a set of tools that enhances the development experience by automating common tasks. The most notable feature is automatic application restart when files change, which is much faster than a full restart because DevTools uses two classloaders – one for your code and another for dependencies that rarely change.
DevTools also includes live reload capability that refreshes your browser automatically when resources change, property defaults optimized for development, and enhanced logging. These features significantly reduce the time between making a change and seeing its effect, allowing for faster iteration and debugging.
Sample Answer: Spring Boot DevTools is a module that streamlines the development process through several key features. Its automatic restart capability detects code changes and restarts the application quickly using a two-classloader approach – one for unchanging dependencies and another for your evolving code. It includes live reload integration that refreshes browsers automatically when static resources change. DevTools also disables template caching and enables debug logging by default. I’ve found it especially valuable for rapid prototyping – in my last project, it reduced our feedback cycle from minutes to seconds when testing UI changes. I simply add the spring-boot-devtools dependency to my pom.xml, and these productivity features activate automatically in development while being disabled in production.
10. What is Spring Initializr? How do you use it to bootstrap a Spring Boot application?
This question helps employers assess your familiarity with standard Spring Boot project setup tools. Knowledge of Spring Initializr shows you follow community best practices for project creation. It indicates you can start new projects efficiently without unnecessary manual configuration.
Spring Initializr is a web-based tool provided by the Spring team that generates project structures with all the necessary configuration files and dependencies. It solves the problem of manually setting up Maven or Gradle configurations and folder structures, which can be error-prone and time-consuming.
To use it, you visit start.spring.io, select your project specifications (Java version, build tool, dependencies), and download the generated project. You can then import this into your IDE as a Maven or Gradle project and start coding immediately. This standardized approach ensures your project follows Spring conventions from the beginning.
Sample Answer: Spring Initializr is a web application at start.spring.io that generates Spring Boot project templates with proper structure and dependencies. To bootstrap a project, I visit the site and configure project metadata (group, artifact, name), specify Java version and build tool (Maven/Gradle), then select dependencies needed for my project. Common selections include Web for REST APIs, JPA for database access, and Security for authentication. After clicking “Generate,” I download a ZIP file containing a complete project structure with properly configured pom.xml/build.gradle. I then import this into my IDE as a Maven/Gradle project, and I’m ready to start coding immediately. This approach ensures consistent project structure and compatible dependency versions without manual setup.
11. How do you implement security in a Spring Boot application?
Employers ask this question to determine your ability to build secure applications, which is critical in today’s environment. Your answer reveals whether you understand security best practices and can protect sensitive data and functionality. This knowledge is increasingly important for all development roles.
The most straightforward approach is using Spring Security, which integrates seamlessly with Spring Boot through the spring-boot-starter-security dependency. Once added, it automatically secures all HTTP endpoints with basic authentication. You can then customize this default behavior based on your requirements.
For custom authentication, you typically implement UserDetailsService and configure security rules in a class annotated with @EnableWebSecurity. You can define authorization rules, configure CSRF protection, session management, and more. For modern applications, you might also implement JWT-based authentication or OAuth2 for API security. The key is balancing security with usability based on your application’s specific needs.
Sample Answer: I implement Spring Boot security in layers, starting with the spring-boot-starter-security dependency. For authentication, I typically create a custom UserDetailsService implementation that connects to our user database. I configure security policies in a @Configuration class with @EnableWebSecurity where I define protected URLs, authentication methods, and authorization rules. For web applications, I implement form-based login with CSRF protection and proper session management. For REST APIs, I’ve implemented JWT authentication with stateless sessions. I always enforce HTTPS in production, secure cookies, implement proper password hashing with BCrypt, and add headers for XSS protection. My approach focuses on defense in depth rather than single-point security measures.
12. Explain the Spring Boot testing features and annotations.
Interviewers ask this to assess your commitment to code quality and familiarity with testing practices. Knowledge of testing indicates you can deliver reliable code and verify its functionality. This skill is highly valued in professional development environments.
Spring Boot offers comprehensive testing support through the spring-boot-starter-test dependency, which includes JUnit, Spring Test, AssertJ, Hamcrest, Mockito, and more. This integrated testing stack covers unit, integration, and end-to-end testing needs without requiring additional configuration.
Key testing annotations include @SpringBootTest for loading the full application context, @WebMvcTest for testing controllers in isolation, @DataJpaTest for repository testing, and @MockBean/@SpyBean for mocking dependencies. Spring Boot also provides TestRestTemplate and WebTestClient for testing REST endpoints. These tools let you test different layers of your application independently and verify interactions between components.
Sample Answer: Spring Boot provides excellent testing support through several specialized annotations and utilities. I use @SpringBootTest for full integration tests that load the entire application context, which is perfect for end-to-end testing. For faster controller tests, I use @WebMvcTest with MockMvc to test only the web layer. When testing repositories, @DataJpaTest configures an in-memory database and focuses on data access components. I use @MockBean to replace real dependencies with Mockito mocks and @AutoConfigureMockMvc to test controllers without starting a server. For testing REST clients, TestRestTemplate and WebTestClient are invaluable. Spring Boot’s slice tests (@DataJpaTest, @WebMvcTest) significantly speed up test execution by loading only relevant beans instead of the entire context.
13. What is the purpose of profiles in Spring Boot? How do you configure and use them?
This question helps employers evaluate your understanding of environment-specific configuration management. Knowledge of profiles shows you can adapt applications for different deployment scenarios. This skill is essential for modern development across multiple environments.
Profiles allow you to define environment-specific configurations within a single application, solving the problem of managing different settings for development, testing, staging, and production. This keeps your codebase consistent while allowing configuration to vary across environments.
You can activate profiles through various methods: in application.properties using spring.profiles.active, as a JVM system property, as an environment variable, or programmatically. Profile-specific properties files like application-dev.properties override default configurations when that profile is active. You can also use @Profile annotations on beans to make certain components available only in specific environments.
Sample Answer: Spring Boot profiles let you customize application behavior for different environments without code changes. I configure profiles using application-{profile}.properties files for environment-specific settings. For example, application-dev.properties might use an H2 database while application-prod.properties connects to PostgreSQL. I activate profiles via spring.profiles.active property set in multiple ways – command line arguments, environment variables, or the default application.properties. For beans that should only exist in certain environments, I use the @Profile annotation. In my current project, we use profiles for database configurations, logging levels, and external service endpoints. This approach keeps environment-specific details out of the codebase and lets us deploy the same artifact across all environments.
14. How do you integrate Spring Boot with databases? Explain the configuration process.
Employers ask this to assess your ability to connect applications with data sources, a fundamental requirement for most business applications. Your answer demonstrates whether you can implement data persistence effectively. This skill is often a core requirement for Spring developers.
Spring Boot simplifies database integration through auto-configuration and starter dependencies. For relational databases, you typically add spring-boot-starter-data-jpa, along with your database driver dependency (like H2, MySQL, or PostgreSQL). Spring Boot then automatically configures a DataSource, EntityManager, and transaction management.
The main configuration happens in application.properties/yml where you specify connection details like URL, username, and password. You can also configure connection pooling, JPA properties, and dialect settings. Spring Boot’s convention-over-configuration approach means that minimal setup is required for common scenarios, while still allowing customization when needed.
Sample Answer: Integrating Spring Boot with databases begins with adding the right dependencies – typically spring-boot-starter-data-jpa plus a database driver like mysql-connector-java. In application.properties, I configure the connection with properties like spring.datasource.url, username, password, and driver-class-name. Spring Boot automatically configures connection pooling (HikariCP by default). For JPA settings, I use properties like spring.jpa.hibernate.ddl-auto to control schema generation and spring.jpa.show-sql for debugging. I create entity classes with JPA annotations (@Entity, @Id) and repository interfaces extending JpaRepository. Spring Boot handles the implementation details, generating the necessary queries. For production, I typically use Flyway or Liquibase for database migrations rather than auto-generation to ensure controlled schema evolution.
15. What are the different ways to run a Spring Boot application?
This question helps interviewers gauge your understanding of deployment options and development workflows. Knowledge of different execution methods shows you can adapt to various development and production environments. This versatility makes you more effective across the full development lifecycle.
The most common method is running the main class with the @SpringBootApplication annotation directly from your IDE. This is convenient during development as it provides debugging capabilities and quick iteration. For command-line execution, you can use Maven or Gradle with goals like mvn spring-boot:run.
For production deployment, you typically package the application as an executable JAR using the Spring Boot Maven or Gradle plugins. This JAR contains all dependencies and an embedded server, making it simple to deploy with a standard java -jar command. Alternatively, you can deploy to servlet containers like Tomcat or package as a WAR file for traditional application servers.
Sample Answer: I run Spring Boot applications in several ways depending on the scenario. During development, I typically run the main application class directly from my IDE, which offers convenient debugging capabilities. From the command line, I use Maven or Gradle with commands like mvn spring-boot:run or ./gradlew bootRun. For production deployment, I package the application as an executable JAR with mvn package and run it using java -jar filename.jar. This works because Spring Boot packages an embedded server within the JAR. I can customize runtime behavior using command-line arguments like --server.port=8081 or --spring.profiles.active=prod. For traditional deployment, I’ve also configured Spring Boot applications as WAR files for deployment to external Tomcat servers using SpringBootServletInitializer.
Wrapping Up
You now have expert-level answers to the most common Spring Boot interview questions. With these responses ready, you can approach your next interview with genuine confidence. Technical interviews become much less stressful when you’ve prepared thoroughly with practical, relevant answers.
Take some time to practice these answers out loud before your interview. The combination of solid Spring Boot knowledge and smooth delivery will set you apart from other candidates and showcase your expertise to potential employers.