Spring Boot 4 vs Spring Boot 3: What Changed?

Spring Boot 4 represents a major new generation of the Spring ecosystem. Developers who have been working with Spring Boot 3 will find that many familiar concepts remain unchanged, but the underlying technology stack has moved forward considerably.

Spring Boot 4 builds on Spring Framework 7 and introduces upgrades across Java enterprise APIs, JSON processing, persistence, testing, embedded servers, observability, native applications, and application development.

In this article, we compare Spring Boot 4 vs Spring Boot 3 and examine the most important changes developers should understand in 2026.

---

Spring Boot 3 vs Spring Boot 4 at a Glance

Feature	Spring Boot 3	Spring Boot 4
Spring Framework	Spring Framework 6.x	Spring Framework 7.x
Minimum Java	Java 17	Java 17
Recommended modern Java	Depends on Boot 3 release	Java 25 generation
Jakarta EE	Earlier Jakarta EE generation	Jakarta EE 11
Servlet API	Earlier Servlet generation	Servlet 6.1
Hibernate ORM	Primarily Hibernate 6.x	Hibernate ORM 7.x
Jakarta Persistence	Earlier JPA generation	Jakarta Persistence 3.2
JSON	Jackson 2	Jackson 3 by default
Validation	Hibernate Validator 8-era stack	Hibernate Validator 9
Testing ecosystem	JUnit 5	JUnit 6 generation
Embedded Tomcat	Tomcat 10.x generation	Tomcat 11
Kotlin	Earlier Kotlin generation	Kotlin 2.2 generation
Native-image ecosystem	GraalVM support	Updated GraalVM generation

The transition is therefore much more than simply changing a version number in pom.xml.

---

1. Spring Framework 7

One of the biggest differences is the underlying Spring Framework.

Spring Boot 3 is associated with the Spring Framework 6 generation.

Spring Boot 4 moves to:

Spring Framework 7

This is important because many of Spring Boot 4’s new capabilities originate in Spring Framework 7.

Conceptually:

Spring Boot 3
      ↓
Spring Framework 6

Spring Boot 4
      ↓
Spring Framework 7

Spring Framework 7 modernizes the framework while retaining the programming model that Spring developers already know.

---

2. Java 17 Remains the Minimum

A common misconception is that Spring Boot 4 requires Java 25.

It does not.

The minimum Java baseline remains:

Java 17

However, the Spring Framework 7 generation embraces newer Java versions, with Java 25 being the current LTS generation.

Therefore:

Minimum Java → Java 17
Modern LTS option → Java 25

This is useful for organizations because they can migrate to Spring Boot 4 without necessarily upgrading every application immediately to Java 25.

At the same time, new projects can take advantage of newer Java capabilities.

---

3. Jakarta EE 11

Spring Boot 4 moves the ecosystem forward to Jakarta EE 11 APIs.

This affects several important technologies used by enterprise Java applications.

These include:

Servlet 6.1
Jakarta Persistence 3.2
Bean Validation 3.1

This matters particularly for applications that interact directly with Jakarta APIs.

For developers who previously migrated from Spring Boot 2 to Spring Boot 3, the familiar javax.* to jakarta.* transition has already occurred.

Spring Boot 4 continues with the jakarta.* namespace but moves to newer versions of those APIs.

---

4. Hibernate ORM 7

Database applications receive another significant upgrade.

Spring Boot 3 applications generally use the Hibernate ORM 6 generation.

Spring Boot 4 moves into:

Hibernate ORM 7

Hibernate is the ORM implementation commonly used underneath Spring Data JPA.

A typical Spring application architecture remains:

Spring Boot
     ↓
Spring Data JPA
     ↓
Jakarta Persistence
     ↓
Hibernate ORM
     ↓
Database

Therefore, developers migrating complex database applications should pay particular attention to Hibernate changes.

Simple repository-based applications may require relatively few modifications, while applications using custom Hibernate APIs, sophisticated mappings, HQL, native queries or advanced persistence features deserve more extensive testing.

---

5. Jakarta Persistence 3.2

The persistence stack also moves to:

Jakarta Persistence 3.2

For a normal Spring Data JPA application, developers will still work with familiar annotations such as:

@Entity
@Id
@GeneratedValue
@OneToMany
@ManyToOne

For example:

@Entity
public class Student {

    @Id
    @GeneratedValue
    private Long id;

    private String name;
}

The basic programming model therefore remains recognizable.

The more significant differences are found in the underlying persistence specifications and Hibernate implementation.

---

6. Jackson 3 Becomes the Default

This is one of the changes developers are most likely to notice during migration.

Spring Boot 3 primarily uses:

Jackson 2

Spring Boot 4 moves to:

Jackson 3

Jackson is widely used for converting Java objects into JSON and JSON into Java objects.

For example, consider:

@GetMapping("/student")
public Student student() {
    return new Student(101, "Juhi");
}

Spring can automatically serialize the returned object into JSON.

A response might look like:

{
  "id": 101,
  "name": "Juhi"
}

The developer does not normally perform this conversion manually.

---

7. Jackson Package Changes

Jackson 3 also introduces an important package change.

Many Jackson 2 classes were located under:

com.fasterxml.jackson

Many Jackson 3 classes have moved to:

tools.jackson

This means applications directly using Jackson classes may require import changes.

This is particularly important when an application contains custom:

• ObjectMapper configuration
• serializers
• deserializers
• modules
• JSON configuration
• message converters

Applications relying mostly on Spring Boot’s default JSON handling may experience a much easier migration.

Spring Boot 4 also provides transitional support for Jackson 2, helping applications migrate gradually.

---

8. Improved Null Safety with JSpecify

Spring Framework 7 introduces comprehensive null-safety improvements based on JSpecify.

Null-related errors remain a common source of bugs in Java applications.

Consider:

String name = null;
System.out.println(name.length());

This produces a:

NullPointerException

Better null-safety metadata allows development tools and static-analysis systems to understand more accurately whether values are expected to be nullable.

This can help detect potential problems earlier during development.

It is particularly useful for:

• IDE inspections
• static analysis
• Kotlin interoperability
• large enterprise codebases

---

9. Tomcat 11

Spring Boot applications commonly use an embedded Tomcat server.

Spring Boot 4 upgrades the embedded server generation to:

Tomcat 11

Tomcat 11 supports the Servlet 6.1 generation required by the newer Jakarta stack.

The convenient Spring Boot experience remains the same.

Developers can still start an application with:

SpringApplication.run(MyApplication.class, args);

without separately installing Tomcat for the typical embedded-server use case.

---

10. JUnit 6 Generation

Testing infrastructure has also moved forward.

Spring Framework 7 embraces the JUnit 6 generation.

Spring Boot developers will continue writing familiar tests, but the underlying testing ecosystem has been modernized.

For example:

@SpringBootTest
class ApplicationTests {

    @Test
    void contextLoads() {
    }
}

Applications with extensive custom testing infrastructure should carefully verify library compatibility during migration.

---

11. New API Versioning Support

Spring Framework 7 introduces built-in support for API versioning.

API versioning is important when REST APIs evolve over time.

For example, an application may need to maintain:

Version 1 → Existing clients

Version 2 → New clients

Previously, developers often implemented their own conventions for API versions.

Spring’s newer API versioning capabilities provide framework-level support for handling evolving APIs.

This is particularly useful for:

• REST APIs
• microservices
• mobile backends
• public APIs
• enterprise integrations

---

12. HTTP Interface Client Improvements

Modern applications frequently communicate with external REST services.

Spring’s HTTP Interface Client allows developers to describe remote HTTP APIs using Java interfaces.

Conceptually:

public interface ProductClient {

    @GetExchange("/products/{id}")
    Product getProduct(@PathVariable int id);
}

Spring Framework 7 improves the configuration and capabilities surrounding HTTP interface clients.

This reduces repetitive HTTP-client code and allows developers to work with strongly typed Java interfaces.

---

13. Core Resilience Features

Modern distributed applications need to deal with temporary failures.

Examples include:

Service unavailable
Network timeout
Temporary database problem
Remote API failure

Spring Framework 7 introduces core resilience capabilities that can help applications handle certain failures more gracefully.

Resilience is especially relevant for:

• cloud applications
• microservices
• distributed systems
• applications consuming external APIs

This reflects the continuing evolution of Spring toward cloud-native application development.

---

14. New JmsClient

Spring Framework 7 introduces a new:

JmsClient

It provides a modern API for working with JMS messaging.

The idea is similar to the evolution of other Spring client APIs toward more fluent and convenient programming models.

This is particularly useful for enterprise applications that use messaging systems.

---

15. Improved Native Application Support

Spring Boot 3 already provided significant support for GraalVM native images.

Spring Boot 4 continues this work with the newer GraalVM generation and updated AOT infrastructure.

A traditional Java application normally runs as:

Application
     ↓
JVM
     ↓
Operating System

A native image can instead be compiled ahead of time into a platform-specific executable.

Potential advantages include:

• Faster startup
• Reduced memory usage in some workloads
• Suitability for containers
• Suitability for certain serverless workloads

Native applications are particularly interesting for modern cloud environments where startup time and resource consumption matter.

---

16. Updated Dependency Ecosystem

A major Spring Boot release also brings major dependency upgrades.

Spring Boot 4’s ecosystem includes newer generations of technologies such as:

Hibernate ORM 7
Hibernate Validator 9
Jackson 3
Tomcat 11
Jetty 12
Kotlin 2.2
JUnit 6
Testcontainers 2
Flyway 11
Kafka 4
Groovy 5

This is one reason a major-version migration should be treated differently from a routine patch update.

---

17. Modularization and Starter Changes

Spring Boot 4 also introduces changes intended to make its modules and dependency structure more focused.

Some starter names and dependency arrangements have changed.

For example, developers should not blindly copy dependency configurations from old Spring Boot tutorials.

When creating a new Spring Boot 4 application, using Spring Initializr is generally the safest approach because it generates dependencies appropriate for the selected Spring Boot generation.

This is especially important for beginners following tutorials written for Spring Boot 2 or early Spring Boot 3.

---

18. What Has NOT Changed?

Despite all these changes, Spring Boot 4 still feels like Spring Boot.

The basic application remains familiar:

@SpringBootApplication
public class Application {

    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}

REST controllers remain familiar:

@RestController
public class HelloController {

    @GetMapping("/hello")
    public String hello() {
        return "Hello Spring Boot 4";
    }
}

Dependency injection remains central to Spring development.

For example:

@Service
public class StudentService {
}

and:

@RestController
public class StudentController {

    private final StudentService service;

    public StudentController(StudentService service) {
        this.service = service;
    }
}

The concepts of:

Controllers
Services
Repositories
Beans
Dependency Injection
Configuration
Spring Data JPA
Spring Security

remain fundamental.

Therefore, knowledge gained while learning Spring Boot 3 remains highly valuable.

---

Spring Boot 3 vs Spring Boot 4 Architecture

The difference can be summarized as:

SPRING BOOT 3

Application
    ↓
Spring Boot 3
    ↓
Spring Framework 6
    ↓
Jakarta APIs
    ↓
Hibernate 6 / Jackson 2
    ↓
Java 17+

Compared with:

SPRING BOOT 4

Application
    ↓
Spring Boot 4
    ↓
Spring Framework 7
    ↓
Jakarta EE 11
    ↓
Hibernate 7 / Jackson 3
    ↓
Java 17+ / Modern Java

The application programming model remains familiar while much of the infrastructure underneath it has advanced.

---

Should You Upgrade from Spring Boot 3 to Spring Boot 4?

For new applications in 2026, Spring Boot 4 is a natural choice when your required libraries and deployment environment support it.

Existing production applications require a more careful decision.

Before upgrading, check:

1. Java version
2. Third-party library compatibility
3. Jackson usage
4. Hibernate-specific code
5. Jakarta API compatibility
6. Test libraries
7. Application-server requirements
8. Deprecated APIs
9. Configuration-property changes
10. Custom Spring integrations

The Spring team recommends that applications on older Spring Boot 3 versions first move to Spring Boot 3.5 before migrating to Spring Boot 4.

This reduces the number of changes being introduced simultaneously.

---

Typical Migration Path

A safer migration path is:

Older Spring Boot 3 Application
             ↓
       Spring Boot 3.5
             ↓
   Fix warnings/deprecations
             ↓
       Update dependencies
             ↓
       Spring Boot 4
             ↓
      Run complete tests

Avoid treating a major framework migration as merely:

<version>3.x.x</version>

changing to:

<version>4.x.x</version>

Complex applications may require source-code and configuration changes as well.

---

Which Version Should Beginners Learn in 2026?

If you are starting Spring Boot from scratch in 2026, learning Spring Boot 4 is a sensible choice.

It introduces you directly to the current Spring generation and technologies such as:

Spring Framework 7
Jakarta EE 11
Hibernate 7
Jackson 3
Modern Java
Modern REST APIs
Cloud-native development

However, understanding Spring Boot 3 remains useful because many existing enterprise applications will continue running on the 3.x generation.

A developer who understands both generations will therefore be better prepared to work with existing systems as well as new projects.

---

Spring Boot 4 vs Spring Boot 3: Final Comparison

Area	Spring Boot 3	Spring Boot 4
Framework generation	Spring 6	Spring 7
Java baseline	17	17
Jakarta generation	Earlier	Jakarta EE 11
Servlet	Earlier generation	6.1
Persistence	Hibernate 6 generation	Hibernate 7 generation
JPA	Earlier Jakarta Persistence	Jakarta Persistence 3.2
JSON	Jackson 2	Jackson 3 default
Validation	Earlier generation	Hibernate Validator 9
Tomcat	10.x generation	11
Testing	JUnit 5 generation	JUnit 6 generation
Null safety	Existing annotations	JSpecify-based improvements
API versioning	Mostly application-defined	Framework-level capabilities
Native applications	Supported	Updated native/AOT ecosystem
Best use	Existing Boot 3 applications	New/current-generation applications

---

Conclusion

Spring Boot 4 is not a complete reinvention of Spring Boot. Instead, it modernizes the platform while preserving the programming model familiar to Java developers.

The most important changes include:

• Spring Framework 7
• Jakarta EE 11
• Hibernate ORM 7
• Jakarta Persistence 3.2
• Jackson 3
• Tomcat 11
• JUnit 6 generation
• JSpecify-based null safety
• API versioning
• HTTP Interface Client improvements
• resilience capabilities
• updated native-image support
• modernized third-party dependencies

For beginners, this means that Spring Boot remains approachable.

For experienced Spring Boot 3 developers, however, the move to Spring Boot 4 should be treated as a major platform migration, particularly when applications depend directly on Jackson, Hibernate, Jakarta APIs or third-party integrations.

Spring Boot 4 therefore represents the next step in modern Java backend development while maintaining the core concepts that made Spring Boot popular in the first place.

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Further Reading

Spring Boot 4 Tutorial for Beginners: Build Your First Application (2026)

Spring Framework 7: New Features Developers Should Know in 2026

What Is Claude AI? A Beginner’s Guide (2026)

Claude Code vs ChatGPT Codex: A Practical Comparison for Developers (2026)

What is MCP? A Beginner’s Guide with Python Examples

MCP vs REST API – Key Differences

Build Your First MCP Server in Python

Create an MCP Server for MySQL Database

Integrate OpenAI Agents with MCP

Security Risks in MCP Servers and How to Mitigate Them

What is n8n? A Beginner-Friendly Guide to Workflow Automation

How to Automatically Publish Blog Posts Using n8n (Step-by-Step Guide)

Top 10 Real-World Use Cases of n8n for Developers

Introduction to Django Framework and its Features

Django Practice Exercise

Examples of Array Functions in PHP

Basic Programs in PHP

Registration Form Using PDO in PHP

Inserting Information from Multiple CheckBox Selection in a Database Table in PHP

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