Top 50 Spring Boot Interview Questions and Answers 2025

Prepare for Spring Boot interviews with questions on microservices, configuration, and REST APIs.

Spring Boot Interview Questions and Answers

1) What is Spring Boot?

Spring Boot is a Spring module that provides RAD (Rapid Application Development) features to the Spring framework.

It is used to create stand-alone spring-based applications that you can just run because it needs very little spring configuration.

2) What are the advantages of Spring Boot?

• Create stand-alone Spring applications that can be started using java -jar.

• Embed Tomcat, Jetty, or Undertow directly. You don't need to deploy WAR files.

• It provides opinionated 'starter' POMs to simplify your Maven configuration.

• It automatically configures Spring whenever possible.

3) What are the features of Spring Boot?

Some key features of Spring Boot include:

• Auto-configuration: It automatically configures application components based on project dependencies.
• Embedded web server support: Spring Boot includes embedded servers like Tomcat, Jetty, and Undertow, making it easy to deploy web applications.
• Spring Boot Starter: Pre-defined templates for common use cases, simplifying dependency management.
• Production: ready metrics, health checks, and externalized configuration.
• Spring Boot CLI: Command Line Interface for rapid application development.

For more information, click here.

4) How to create a Spring Boot application using Maven?

There are multiple approaches to creating a Spring Boot project. We can use any of the following approaches to develop an application.

• Spring Maven Project
• Spring Starter Project Wizard
• Spring Initializr
• Spring Boot CLI

For more information, click here.

5) How to create a Spring Boot project using Spring Initializer?

It is a web tool that is provided by Spring on the official site. You can create a Spring Boot project by providing project details.

For more information, click here.

6) How to create a Spring Boot project using boot CLI?

It is a tool that you can download from the official site of Spring Framework. Here, we are explaining the steps.

Download the CLI tool from the official site, and For more information, click here.

7) How to create a simple Spring Boot application?

To create an application, we can use STS (Spring Tool Suite) IDE. It includes the various steps that are explained in steps.

For more information, click here.

8) What are the Spring Boot Annotations?

Spring Boot annotations are metadata that provides instructions to the Spring framework, simplifying configuration and reducing boilerplate code. 

Annotations caused major changes in programming style and slowly made the XML-based configurations outdated. The Java Programming introduced support for Annotations from JDK 1.5. However, Spring Framework started supporting annotations from the release 2.5.

Some key annotations are:

• @SpringBootApplication
• @RestController
• @RequestMapping
• @GetMapping 
• @PostMapping
• @PutMapping
• @DeleteMapping

For more information, click here.

9) What is Spring Boot dependency management?

Spring Boot manages dependencies and configuration automatically. We do not need to specify the version for any of those dependencies.

Spring Boot upgrades all dependencies automatically when you upgrade Spring Boot.

For more information, click here.

10) What are the Spring Boot properties?

Spring Boot provides various properties that can be specified inside our project's application.properties file. These properties have default values and you can set that inside the properties file. Properties are used to set values like server port number, database connection configuration, etc.

For more information, click here.

11) What are the Spring Boot Starters?

Starters are a set of convenient dependency descriptors that we can include in our application.

Spring Boot provides built-in starters which makes development easier and rapid. For example, if we want to get started using Spring and JPA for database access, just include the spring-boot-starter-data-jpa dependency in your project.

For more information, click here.

12) What is a Spring Boot Actuator?

Spring Boot provides an actuator to monitor and manage our application. The actuator is a tool that has HTTP endpoints. When the application is pushed to production, you can choose to manage and monitor your application using HTTP endpoints.

For more information, click here.

13) What is thymeleaf?

It is a server-side Java template engine for web applications. Its main goal is to bring elegant natural templates to your web application.

It can be integrated with Spring Framework and is ideal for HTML5 Java web applications.

For more information, click here.

14) How to use thymeleaf?

In order to use Thymeleaf, we must add it into our pom.xml file like:

1. <dependency>
2. <groupId>org.springframework.boot</groupId>
3. <artifactId>spring-boot-starter-thymeleaf</artifactId>
4. </dependency>

For more information, click here.

15) How to connect Spring Boot to the database using JPA?

Spring Boot provides spring-boot-starter-data-jpa starter to connect Spring applications with relational databases efficiently. You can use it in the project POM (Project Object Model) file.

For more information, click here.

16) How to connect the Spring Boot application to the database using JDBC?

Spring Boot provides starters and libraries for connecting to our application with JDBC. Here, we are creating an application that connects with the MySql database. It includes the following steps to create and set up JDBC with Spring Boot.

For more information, click here.

17) What is @RestController annotation in Spring Boot?

The @RestController is a stereotype annotation. It adds @Controller and @ResponseBody annotations to the class. We need to import org.springframework.web.bind.annotation package in our file in order to implement it.

For more information, click here.

18) What is @RequestMapping annotation in Spring Boot?

The @RequestMapping annotation is used to provide routing information. It tells the Spring that any HTTP request should map to the corresponding method. We need to import org.springframework.web.annotation package in our file.

For more information, click here.

19) How to create a Spring Boot application using Spring Starter Project Wizard?

There is one more way to create a Spring Boot project in STS (Spring Tool Suite). Creating a project by using IDE is always a convenient way. Follow the following steps in order to create a Spring Boot Application by using this wizard.

For more information, click here.

20) What are the major differences between Spring Vs. Spring Boot?

Spring is a web application framework based on Java. It provides tools and libraries to create a completely customized web application.

Spring Boot is a spring module that is used to create a spring application project that can just run.

21) In how many ways Spring Boot applications can be packaged for deployment?

Spring Boot Applications can be packaged for deployment in the following ways.

22) What are Spring Boot profiles, and how are they useful?

Spring Boot profiles are used to define sets of configuration properties for different environments or scenarios. It allows the developer to customize application behavior for development, testing, production, etc., by providing different property files (for example, application-dev.properties, application-prod.properties). Spring Boot will activate the appropriate profile based on the active environment.

23) How can you monitor and manage Spring Boot applications in a production environment?

In a production environment, we can monitor and manage Spring Boot applications by using tools like Spring Boot Actuator. It provides endpoints for health checks, metrics, and logging. For in-depth application monitoring and management, we can integrate monitoring solutions like Prometheus and Grafana.

24) What is the purpose of the Spring Boot CLI

The Spring Boot CLI (Command Line Interface) is a command-line tool. It allows developers to create, run, and manage Spring Boot applications quickly. It provides features like application generation, embedded server support, and easy dependency management. The CLI is especially useful for rapid prototyping and development. The most commonly used CLI commands are:

• -run
• -test
• -jar
• -war
• –init
• -help

25) What is the purpose of using @ComponentScan annotation in the Class Files?

The annotation @ComponentScan is used to specify the packages to scan for annotated components. It helps Spring to detect and register beans with annotations like @Component, @Service, @Repository, and @Controller automatically.

26) What are Spring Boot Actuator endpoints commonly used for monitoring and management of Spring Boot applications?

Spring Boot Actuator

provides various endpoints for monitoring and managing applications. Some commonly used endpoints are as follows:

• /actuator/health: It provides application health status.
• /actuator/info: It provides custom application information.
• /actuator/metrics: It exposes application metrics (for example, memory usage and request counts).
• /actuator/env: It displays environment properties.
• /actuator/loggers: It allows dynamic log-level configuration.

27) How do you enable an SSL certificate in a Spring Boot application? 

1. Get a certificate from a Certificate Authority (CA).
2. Set up SSL properties in application.properties, including keystore path, password, and key alias.
3. Ensure that the server is configured to use HTTPS by setting the appropriate properties.

28) What is Spring Boot caching support, and why is it useful?

Spring Boot provides caching support through annotations like @Cacheable, @CacheEvict, and @CachePut. It is used to improve application performance by storing frequently accessed data in memory. Spring Boot simplifies the setup and management of caching mechanisms, such as Ehcache, Caffeine, and Redis, making it easier to implement caching strategies.

29) How can we schedule tasks in a Spring Boot application?

We can create and schedule tasks in Spring Boot by using the @Scheduled annotation in combination with a method in a Spring-managed bean. It allows us to define the execution interval or cron expressions to specify when the task should run. Scheduling tasks are commonly used for background jobs, batch processing, and periodic tasks.

30) Explain the Spring Boot application structure.

Spring Boot project follows a specific directory structure:

• src/main/java: It contains the Java source code.
• src/main/resources: It contains configuration files, templates, and other non-Java resources.
• src/test/java: It is a community of test cases and test-related code.
• src/test/resources: It stores test-specific resources.
• xml: It contains and manages dependencies and build settings.

31) What is Spring Boot DevTools, and how does it help in development?

Spring Boot DevTools — a module that provides the developer with some development-time features, such as automatic application restart, live reloading of changes, and improved error reporting. It is also better for the developer experience and helps in faster development by eliminating the time spent restarting and recompiling the application manually.

32) Is it possible to disable the default web server in the Spring Boot application?

Yes, it is possible to disable the default web server in the Spring Boot. We can disable it by setting the property server.port to “-1” in the application.properties file.

33) What type of applications can we design with the Spring Boot?

Besides the web applications, we can design non-web applications, console applications, batch applications, and microservices with the help of Spring Boot.

34) What are the differences between RequestMapping and GetMapping?

35) What are the differences between @Controller and @RestController?

36) How to enable the debugging log in the Spring Boot application?

Debugging logs can be enabled in the following three ways:

• Start the application with the --debug switch.
• Set the level.root=debug property in the application.property file.
• Set the logging level of the root logger to debug in the supplied logging configuration file.

37) How to handle data validations in the Spring Boot application?

There are various mechanisms to handle data validations in the Spring Boot application. The most used way to do that is to leverage validation annotations defined by the Bean Validation API. For example, @NotNull, @Size, and @Pattern. It is used on the fields of object model.

By implementing these validation annotations, the Spring Boot application automatically validates the data and generates the validation errors. It also enables us to have our own validation logic by writing validation classes and methods.

38) What do you mean by Bean scope in Spring Boot?

Bean Scopes in Spring Boot application Bean scopes in Spring Boot application define the lifecycle and visibility of Spring-managed beans. The following are the most commonly used bean scopes:

• Singleton: A single instance of the bean will be created and shared in the entire application context.
• Prototype: Each time a request is made for the bean, a new instance of it is instantiated.
• Request: A new bean instance is created on every HTTP request. But it's only valid in a web application context.
• Session: A new bean instance will be created per user session. It applies just pertaining to web applications.
• Custom Scopes: We can define our own scopes in Spring Boot by implementing the Scope interface and registering custom scopes in the application context.

39) How to optimize Spring Boot application startup time?

• Reducing the number of beans loaded.
• Using lazy initialization.
• Restricting unused auto-configurations.
• Analyzing startup logs to identify slow components.

40) How do we manage database transactions in a Spring Boot application?

When managing database transactions, Spring Boot provides @Transactional annotation. By implementation, Spring Boot automatically operates transaction boundaries. Additionally, Spring Boot is integrated into a variety of data sources and JPA providers for uniform transaction management.

41) How do you deal with Spring Boot memory management?

We can handle memory management in the Spring Boot application as follows:

• Monitoring memory usage with Actuator endpoints.
• Configuring heap size and garbage collection settings.
• Detect memory leaks by using the profiling tools.
• Optimizing code to reduce memory footprint.

42) Which tools and libraries are helpful for Spring Boot development? 

For Spring Boot application development, helpful tools and libraries include Spring Tool Suite (STS), IntelliJ IDEA, Lombok, and MapStruct.

43) How to activate the debugging Log in the Spring Boot application?

To enable debugging logs, add the following property in the application.properties file:

logging.level.org.springframework=DEBUG

It sets the log level to DEBUG for the Spring framework.

44) What is the benefit of externalized configuration supported by Spring Boot?

Spring Boot allows us to externalize configuration properties using properties files (for example, application.properties or application.yml). These properties can be stored outside the application code and changed without recompiling the application. Spring Boot also supports environment-specific configuration through profile-specific property files (for example, application-dev.properties for development).

45) How does the Constructor differ from the Setter Injection?

46) Excluding the Tomcat server, name any two embedded servers supported by Spring Boot.

There are the following two most commonly used embedded servers are as follows:

• Jetty
• Undertow

47) How can we secure a Spring Boot application?

We can secure a Spring Boot application using various methods as follows:

• Spring Security: Utilize Spring Security to configure authentication and authorization.
• OAuth2: Implement OAuth2 for token-based authentication and authorization.
• JWT (JSON Web Tokens): Use JWTs for stateless authentication.
• HTTPS: Enable HTTPS for secure communication.

48) How to configure a database in Spring Boot?

The following configuration is required to configure the database in the Spring Boot application. This configuration must be specified in the application.properties file.

49) What are the advantages of the YAML file compared to the application.properties file, and what are the different ways to load it? 

YAML files provide a clearer and more user-friendly environment for developers. They also support maps, lists, and other data types. Their hierarchical nature helps avoid repetition and unnecessary indentations.

Consider a scenario with different deployment profiles, such as development, testing, or production. In this case, we might have various configurations for each environment. Instead of creating separate files for each environment, we can consolidate them into a single YAML file. However, we cannot do the same with properties files.

50) Give some examples of applications or services that use Spring Boot.

There are the following top 10 originations that use Spring Boot:

1. Udemy
2. Paytm
3. Trivago
4. Intuit
5. Cred
6. Rappi
7. Quinto Andar
8. MercadoLibre
9. PedidosYa
10. iFood