Following the announcement of the strategic partnership between JetBrains and Spring in May, I would like to share a global update on various Kotlin-related features and documentation enhancements we have made recently, with the goal of making Spring Boot 4 the best framework to develop backend applications with Kotlin.

This is a new blog post in the Road to GA series, this time sharing an update on the status of the null-safety support across the Spring portfolio, as a follow-up of my previous related blog post Null Safety in Spring applications with JSpecify and NullAway and related Spring I/O talk.

This is a new blog post in the Road to GA series, this time sharing more details on the new Jackson 3 support, just a few days after Jackson 3.0.0 GA release, about to be introduced in Spring Boot 4 and related Spring portfolio projects.

Jackson is by far the most used JSON library on the JVM, and the introduction of the Jackson 3 support in Spring is the opportunity for us to provide additional enhancements, as a follow-up of the popular Jackson integration improvements in Spring that I announced more than 10 years ago!

Note: a follow-up blog post Null-safe applications with Spring Boot 4 has been published.

The initial introduction of the null safety support in Spring dates back to 2017 and the release of Spring Framework 5.0. In 2025, we are evolving that story to bring more added value for Spring developers, either in Java or Kotlin. But before having a deeper look to the changes we are working on, let me explain why we do that and what are the expected benefits.

How can Spring Boot developers improve the runtime efficiency of their applications with minimal constraints in order to enjoy those benefits on most applications? The answer is the CDS support introduced by Spring Boot 3.3 which allows you to start your Spring Boot applications faster and consume less memory. It is based on the foundation introduced by Spring Framework 6.1 that I presented a few months ago.

A key point is that this new CDS support provides a different value proposition compared to the GraalVM native image support: the improvements you get with CDS are less dramatic than with…

On behalf of the team and everyone who has contributed, I am pleased to announce that Spring Framework 6.1.4, 6.0.17 and 5.3.32 are available now.

Spring Framework 6.1.4 ships with 106 fixes and documentation improvements. This version will be shipped with Spring Boot 3.2.3, to be released next week.

Spring Framework 6.0.17 ships with 17 fixes and documentation improvements. This version will be shipped with Spring Boot 3.1.9, to be released next week.

Spring Framework 5.3.32 ships with 19 fixes and documentation improvements.

The releases address CVE-2024-22243 for URL Parsing with Host…

As a follow-up to the Runtime efficiency with Spring blog post, I am happy to share that our exploration of Project Leyden optimizations has led to some interesting discoveries regarding the JDK's little-used CDS ("Class Data Sharing") feature and has materialized into a new feature that we have been able to ship in Spring Framework 6.1.

As stated in the official documentation, Class Data Sharing (CDS) helps reduce the startup time and memory footprint of JVMs by caching class metadata in an archive file so that it can be quickly pre-loaded into a newly launched JVM. This accelerates class…

With Spring Framework 6.1 and Spring Boot 3.2 general availability approaching, we would like to share an overview about several efforts the Spring team is pursuing to allow developers to optimize the runtime efficiency of their applications.

We are going to cover the following technologies and use cases:

• Spring MVC as a lean Virtual Threads web stack on JDK 21
• Optimized container deployment with Spring and GraalVM Native Image
• JVM Checkpoint Restore: Scale to zero with Spring and Project CRaC
• A glimpse into OpenJDK’s future with Spring AOT and Project Leyden

If you prefer watching a video…

Today, we are finishing to transition the Spring support for building native executables from the experimental Spring Native project to the official Spring Boot GraalVM native image support.

In practice, that means we are archiving the Spring Native GitHub repository and moving it to the https://github.com/spring-attic organization. There will be no new release of Spring Native (based on Spring Boot 2.x) and we are encouraging all Spring Boot users to migrate to Spring Boot 3.x to leverage its official native support.

On behalf of the team and everyone who has contributed, I am pleased to announce that Spring Framework 6.0.0-RC3 is available now.

Spring Framework 6.0.0-RC3 includes 22 fixes and improvements. This is the last release candidate expected before the general availability of Spring Framework 6.0.0 currently planned mid-November.

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