Top 9 Must-Read Spring Boot Interview Questions for 2026

Spring Boot is one of the most popular frameworks for building enterprise Java applications today. As a highly productive framework built on top of the Spring ecosystem, Spring Boot dramatically simplifies and speeds up Java development.

If you‘re preparing for a Spring Boot job interview in 2024, you‘ve come to the right place. In this in-depth article, we‘ll cover 9 essential Spring Boot interview questions that will test your knowledge of the framework. Whether you‘re an experienced Spring Boot developer or just starting out, understanding these core concepts will help you excel in your next interview.

Let‘s dive in!

1. What are the key benefits of using Spring Boot?

Spring Boot offers many advantages that make it a top choice for Java developers:

Increased Productivity – Spring Boot is designed to get you up and running as quickly as possible. It takes an opinionated view of the Spring platform, letting you focus on building features instead of configuring boilerplate code. With auto-configuration, starter dependencies, and production-ready features out of the box, you can bootstrap a new Spring Boot project in minutes.

Rapid Application Development – Spring Boot‘s auto-configuration and starter dependencies enable developers to quickly assemble and deploy applications. You can create standalone, production-grade Spring applications with minimal fuss.

Embedded Server Support – Spring Boot includes an embedded servlet container (like Tomcat or Jetty) so you can run web applications without needing to deploy WAR files. This also makes it easy to create self-contained, deployable JAR files.

Externalized Configuration – Spring Boot allows you to externalize your configuration so you can work with the same application code in different environments. You can easily configure your application using properties files, YAML files, environment variables, command-line arguments, and more.

Production-Ready Features – Spring Boot provides many features that are ready for production use out-of-the-box, such as metrics, health checks, externalized configuration, and more. These help you monitor and manage your applications in production with minimal effort.

2. What is Spring Cloud and what are its key features?

Spring Cloud is a collection of tools for developing common distributed systems patterns in Spring Boot applications. It aims to simplify the development of cloud-native applications by providing integrations with popular tools and frameworks in the cloud computing space.

Some of the key features of Spring Cloud include:

Distributed Configuration – Spring Cloud Config provides server and client-side support for externalized configuration in a distributed system. With Config Server, you have a central place to manage external properties for applications across all environments.

Service Discovery – Spring Cloud supports service discovery through integrations with tools like Netflix Eureka, Consul, or Zookeeper. This allows services to find and communicate with each other without hard-coding hostname and port.

Circuit Breakers – Spring Cloud Circuit Breaker provides an abstraction across different circuit breaker implementations. A circuit breaker allows you to build fault-tolerant applications that limit the impact of failures and latency spikes in distributed systems.

API Gateway – Spring Cloud Gateway aims to provide a simple, yet effective way to route to APIs and provide cross cutting concerns such as security, monitoring/metrics, and resiliency.

Client-Side Load Balancing – Spring Cloud Load Balancer provides client-side load balancing for HTTP and TCP-based services. Integrations are provided for popular frameworks like Netflix Ribbon.

Distributed Tracing – Spring Cloud Sleuth implements a distributed tracing solution compatible with Zipkin, a popular open source distributed tracing system.

Overall, Spring Cloud aims to boost productivity for developers building Java applications for the cloud. It operationalizes proven patterns through framework integrations that work seamlessly with Spring Boot.

3. What are the main dependencies needed for a Spring Boot project?

While the exact dependencies will vary based on your project‘s requirements, there are some common starters and libraries used in most Spring Boot applications:

spring-boot-starter-parent – This is the parent POM providing dependency and plugin management for Spring Boot applications. Using this parent POM lets you omit version tags for common dependencies.

spring-boot-starter-web – This starter is used for building web applications, including RESTful applications, using Spring MVC and Tomcat as the default embedded container.

spring-boot-starter-data-jpa – The JPA starter is used for Spring Data JPA with Hibernate as the default JPA provider. It brings in all the required dependencies for working with relational databases using JPA.

spring-boot-starter-security – This starter is used for Spring Security, providing authentication and authorization support for Spring Boot applications.

spring-boot-starter-test – The test starter brings in the dependencies for unit testing and integration testing Spring Boot applications. It includes JUnit, Mockito, AssertJ, and other popular testing frameworks.

spring-boot-devtools – This library provides fast application restarts, LiveReload, and other development-time features to boost productivity during development.

4. How do you resolve the whitelabel error page in a Spring Boot application?

The "Whitelabel Error Page" is a default error page shown by Spring Boot when your application throws an exception and no specific error page is configured. While it‘s useful for debugging during development, you‘ll want to replace it with a custom error page in production.

There are a few ways to resolve the whitelabel error page:

1. Implement a Custom Error Controller – You can implement the ErrorController interface and override its getErrorPath() method to provide a custom route when an error occurs. This gives you complete control over the error handling.

2. Provide a Custom Error Page – By convention, Spring Boot looks for a template named "error.html" in the src/main/resources/templates directory. If you create this template, it will be rendered as the custom error page.

3. Disable the Whitelabel Error Page – If you don‘t need a custom error page, you can simply disable the whitelabel page by setting this property in your application.properties file:
   
server.error.whitelabel.enabled=false


5. How does Spring Boot compare to frameworks like JAX-RS?

While both Spring Boot and JAX-RS (Java API for RESTful Web Services) can be used to build RESTful web services in Java, Spring Boot offers some key advantages:

Opinionated Defaults – Spring Boot takes an opinionated view, favoring convention over configuration. It provides sensible defaults out of the box, reducing the amount of configuration required. JAX-RS is less opinionated, requiring more configuration by the developer.

Comprehensive Ecosystem – Spring Boot benefits from the extensive Spring ecosystem, providing integrations with a wide variety of popular frameworks and libraries. This breadth of integrations is a key strength of Spring Boot.

Auto-configuration – Spring Boot‘s auto-configuration feature automatically configures your application based on the dependencies present on the classpath. This dramatically reduces the amount of configuration required. JAX-RS does not provide auto-configuration.

Production-Ready Features – Spring Boot includes many features ready for production use, such as metrics, health checks, and externalized configuration. While you can add these to a JAX-RS application, they are not provided out of the box.

Embedded Server Support – Spring Boot lets you run your application as a standalone application with an embedded server. With JAX-RS, you typically need to deploy your application to an external server.

6. What are "starters" in Spring Boot?

Starters are a key feature of Spring Boot that allow you to add jars to your classpath with minimal fuss. A starter is essentially a set of convenient dependency descriptors that you can include in your application to get a set of dependencies.

For example, if you want to get started using Spring and JPA for database access, you can simply include the spring-boot-starter-data-jpa dependency in your project. This starter will bring in all the necessary dependencies, such as Spring Data JPA, Hibernate, and the necessary Spring libraries.

Starters are designed to work together, so you can stack them to create a production-ready application with minimal effort. They also provide a consistent, supported way of using popular frameworks and libraries with Spring Boot.

7. What are the advantages of using YAML configuration files in Spring Boot?

While Spring Boot supports both properties files and YAML files for configuration, YAML files offer some distinct advantages:

Hierarchical Structure – YAML files use indentation to represent a hierarchical structure, making them very readable and less verbose than properties files. This hierarchy also allows for easy grouping of related properties.

Support for Arrays and Collections – YAML files have built-in support for arrays and collections, making it easy to specify a list of values for a property. Doing the same in a properties file is more cumbersome.

Support for Multiple Profiles – With YAML files, you can specify configuration for multiple profiles (e.g., development, staging, production) in the same file, separated by a "—" line. This is not possible with properties files, which require separate files for each profile.

Here‘s an example of how you might specify configuration for multiple profiles in a YAML file:


spring:
profiles: development

server:
port: 80


8. What‘s the difference between @Controller and @RestController in Spring Boot?

Both @Controller and @RestController are used to define controller classes in Spring Boot, but they serve different purposes.

@Controller is the standard annotation used to define a controller in a Spring MVC application. When you annotate a class with @Controller, you‘re indicating that the class is a web controller, capable of handling HTTP requests. @Controller classes typically return a view name, which is then resolved by a view resolver to render the HTML.

@RestController, on the other hand, is a specialized version of @Controller, used to build REST APIs. It‘s a convenience annotation that combines @Controller and @ResponseBody. When you annotate a class with @RestController, every method in the class automatically has the @ResponseBody annotation, meaning the return value of each method is written directly to the HTTP response body, instead of being resolved to a view.

Here‘s an example of a simple @RestController:


@RestController
public class GreetingController {

@GetMapping("/greeting")
public String greet() {
    return "Hello, World!";
}

}


In this example, when a GET request is made to "/greeting", the greet() method is invoked, and the string "Hello, World!" is written directly to the HTTP response body.

9. How do you test and monitor Spring Boot applications?

Spring Boot provides excellent support for testing and monitoring your applications.

For testing, Spring Boot provides a spring-boot-starter-test starter which brings in the most commonly used testing dependencies. This includes the Spring Test framework, JUnit, Mockito, AssertJ, and more. Spring Boot also provides a @SpringBootTest annotation which you can use to create an application context during integration tests.

Here‘s a simple example of a Spring Boot integration test:


@SpringBootTest
public class MyApplicationTest {

@Autowired
private MyController controller;

@Test
public void contextLoads() {
    assertThat(controller).isNotNull();
}

}


For monitoring, Spring Boot provides several production-ready features out of the box. This includes:

Actuator Endpoints – Spring Boot Actuator provides a number of endpoints that let you monitor and interact with your application. This includes endpoints for health checks, metrics, logging, and more.

Micrometer Integration – Spring Boot includes Micrometer, an application metrics facade that supports numerous monitoring systems. This allows you to capture metrics from your application and ship them to a variety of backends, such as Prometheus, Graphite, New Relic, etc.

Health Indicators – Spring Boot introduces the concept of Health Indicators, which are used to check the health of the application. You can create custom health indicators to check the status of your application‘s dependencies, such as databases, message brokers, or external web services.

Tracing and Logging – Spring Boot integrates with popular tracing solutions like Spring Cloud Sleuth and Zipkin to provide distributed tracing for microservices. It also provides a robust logging system, allowing you to configure log levels, log output format, and log output destinations.

Conclusion

In this article, we covered 9 essential Spring Boot interview questions. We started by discussing the key benefits of Spring Boot, such as increased productivity, rapid application development, and production-ready features. We then explored Spring Cloud and its main features, common Spring Boot dependencies, resolving the whitelabel error page, comparing Spring Boot to JAX-RS, understanding starters and YAML configuration, the difference between @Controller and @RestController, and finally, testing and monitoring Spring Boot applications.

Understanding these core concepts will give you a solid foundation in Spring Boot and prepare you for your next interview. Remember, Spring Boot is a vast ecosystem with a lot to learn. The best way to prepare is to practice building applications, explore the official documentation, and stay up-to-date with the latest releases.

Best of luck in your interviews!