Spring Boot 4.0 Preview: Key New Features, Roadmap, and Upgrade Guide

Major Milestones and Version Progress

Spring Boot 4.0 is currently in preview, with the GA planned for November 2025 alongside Spring Framework 7.0. The roadmap includes:

May 2025 – 4.0.0 Preview : Available in Spring Initializr, built on Spring Framework 7.0, requires Java 17 (compatible up to Java 25), recommends Java 21.

July 2025 – 4.0.0‑M1 : Full modular refactor into dozens of independent modules (e.g., spring‑boot‑webmvc, spring‑boot‑data‑jpa), streamlined starters, and support for Spring Batch 6.

September 2025 – RC candidate : Feature freeze, focus on defect fixes.

Mid‑November 2025 – GA : Production‑ready release synchronized with Spring Framework 7.0.0 GA.

Core New Features Overview

Elegant API versioning : Use the version attribute of @RequestMapping to route based on request header or query parameter without separate URIs.

BeanRegistrar : Introduces a BeanRegistrar interface for programmatic, conditional batch bean registration, increasing flexibility.

Null‑safety with JSpecify : Full integration of JSpecify annotations such as @Nullable and @NonNull for compile‑time null‑pointer protection.

Declarative HTTP service proxies : Annotations like @ImportHttpServices simplify creation and management of HTTP client proxies, reducing boilerplate.

Deep cloud‑native and performance optimizations

GraalVM native image support : Applications can be compiled to native executables, achieving sub‑second startup and minimal memory usage, ideal for serverless.

Virtual thread integration : Leverages JDK 21 virtual threads to boost throughput in high‑concurrency scenarios.

Performance gains : Certain workloads see up to 800 % improvement.

Version Support Strategy Adjustments

Long‑Term Support (LTS) : Spring Boot 3.5 becomes the new LTS baseline.

Support lifecycle : The final minor release of each major line (e.g., 3.5) receives over seven years of support (13 months open‑source, 12 months regular enterprise, plus 5 years LTS enterprise).

Full‑stack alignment : All Spring projects will align their support cycles with the corresponding Spring Boot version, simplifying compatibility decisions.

Upgrade Considerations

JDK version : Minimum Java 17, recommended Java 21 LTS.

Jakarta EE migration : Ensure code and dependencies have moved from javax to jakarta namespaces.

Build tools : Use Maven 3.6.3+ or Gradle 7.6.4+ (or 8.4+).

Application server : Deploy on servers supporting Servlet 6.1+, such as Tomcat 11+ or Jetty 12.1+.

Conclusion

Spring Boot 4.0 represents a major step toward cloud‑native, modern Java development, delivering substantial performance improvements, a smoother developer experience, and richer built‑in capabilities. Although the GA is still pending, familiarizing yourself with these features and preparing the required JDK and Jakarta EE changes is a prudent move before the official release.