What's New in Spring Boot 3

Spring Boot 3 is the most significant release in years. Here's what changed and why it matters.

Java 17 baseline

Spring Boot 3 drops support for Java 8 and 11. The minimum is now Java 17, which means records, sealed classes, and text blocks are first-class citizens throughout your application.

GraalVM Native Image support

For the first time, Spring Boot applications can be compiled to a native binary using GraalVM. The result: startup in milliseconds and drastically lower memory usage — ideal for serverless and container workloads.

./mvnw -Pnative native:compile
java -jar target/myapp  # starts in < 100ms

Observability with Micrometer Tracing

Spring Boot 3 ships Micrometer Tracing as a first-class citizen. Distributed traces flow automatically through RestClient, WebClient, and Spring MVC.

management:
  tracing:
    sampling:
      probability: 1.0
  zipkin:
    tracing:
      endpoint: http://localhost:9411/api/v2/spans

New RestClient (replaces RestTemplate)

RestClient client = RestClient.create("http://api.example.com");
String body = client.get()
    .uri("/users/{id}", 1)
    .retrieve()
    .body(String.class);

Migrating from Spring Boot 2

The main breaking changes:

• javax.* → jakarta.* package rename (most significant change)
• Spring Security's WebSecurityConfigurerAdapter is removed — use SecurityFilterChain beans instead
• spring.redis.* properties renamed to spring.data.redis.*