What is Spring Boot? — Spring Technical Interview Questions & Answers

An opinionated, convention-over-configuration layer on top of Spring.

What is Spring Boot?

  • Spring Boot helps you build Java apps faster with less setup work.
  • Built on Spring: Boot does not replace Spring. It configures Spring for you.
  • Auto-configuration: Boot looks at your libraries and sets up common beans automatically.
  • Starters: One dependency (like spring-boot-starter-web) pulls a full ready set of libraries.
  • Embedded server: Tomcat (or Jetty/Undertow) runs inside your app — no separate server install for demos.
  • Why people use it: Less XML, faster first API, production helpers like Actuator.
  • Saying Boot is a different language. It is still Java + Spring.
  • Spring Boot = Spring + auto-configuration + starters + embedded server.

Technical Interview Tip: One line: Boot makes Spring apps production-ready with less manual config.

Code Examples for What is Spring Boot?

What is Spring Boot? — working example

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@SpringBootApplication // config + auto-config + component scan
public class DemoApplication {
  public static void main(String[] args) {
    SpringApplication.run(DemoApplication.class, args);
  }
}

@RestController
class HelloController {
  @GetMapping("/api/hello")
  String hello() {
    return "Hello Spring Boot";
  }
}

What is Spring Boot? — spring Boot is opinionated Spring: starters + auto-configuration + embedded server for fast apps.

How to Explain What is Spring Boot? to an Interviewer

What is Boot (sb intro)?

Used for a tiny REST app localhost:8080 Not just the heading

Give one small example of Boot (sb intro).

@SpringBootApplication + one controller An opinionated, convention-over-configuration layer on top of Spring

What mistake do beginners make with Boot (sb intro)?

calling Boot ‘just Spring XML’ Show the fix

Where do you use Boot (sb intro)?

localhost:8080 a tiny REST app