Spring I/O is an annual event that has become a key meeting point for Java and Spring developers worldwide.
This year’s main focus? The upcoming Spring Framework 7.0 and Spring Boot 4.0, marking a major baseline upgrade after three years.
Here are the top highlights and announcements from the event:
🚀 Major Themes and Updates
✅ Baseline Update
While the official JDK baseline for Spring 7.0 will remain JDK 17, the Spring team strongly recommends migrating to JDK 25. This will be the next Long-Term Support (LTS) version of Java when Spring Framework 7.0 is released.
Why? Performance improvements in JDK 24 and 25 will benefit Spring apps automatically, without needing code changes.
✅ Jakarta EE 11
Spring Framework 7.0 and Spring Boot 4.0 will now focus on Jakarta EE 11, adopting updates like Servlet 6.1, JPA 3.2, and Bean Validation 3.1.
Spring is also preparing for future evolution of these specifications, with planned support for providers like Tomcat 11, Hibernate ORM 7, and Hibernate Validator 9.0.
✅ Kotlin 2 Integration
Spring will now support the new Kotlin 2 series, improving reflection efficiency and making Kotlin an even stronger first-class citizen for Spring app development.
✅ Better Nullability with JSP Specify
Spring will adopt JSP Specify, a new set of annotations to declare nullability in API signatures.
This is a big step forward from Spring's previous custom nullability annotations. It’s also one of the first large-scale uses of Java’s type-use annotation feature.
👉 Developers are encouraged to adopt JSP Specify to make APIs safer against null issues.
Watch the Sébastien Deleuze talk to learn more about it: Null Safety in Java with JSpecify and NullAway by Sébastien Deleuze @ Spring I/O 2025
✅ Performance and Memory Optimizations
Spring continues investing in native image support and AOT processing, with extra focus thanks to the Project Leyden initiative in the JDK.
Leyden aims to improve startup time and warm-up time for Java apps through new AOT compilation features in JDK 24 and 25.
Up to 4.4x faster startup time for Spring Boot Hello World apps (JDK 24 with AOT enabled).
Improved warm-up time.
Watch the session: Step up the performance game with Spring Boot and Project Leyden by Moritz Halbritter
✅ Spring AI 1.0 GA
A major announcement was the general availability of Spring AI 1.0 – providing Java developers with tools to build Generative AI applications, including:
Retrieval-Augmented Generation (RAG)
Chat memory management
Tool calling
Support for 20+ vector stores and LLM models
Spring AI also helps with context sharing across ecosystems via the Model Context Protocol (MCP) and supports agentic patterns.
Watch the session: Code Smarter, Not Harder: AI-Powered Dev Hacks for All by Dan Vega @ Spring I/O 2025
✅ Want to learn more?
Stay tuned for session replays and upcoming resources directly from the Spring I/O channel.
💬 Have you watched another session that you really liked? Please share it in the comments!
Very cool, man. Is Spring now a viable alternative to Quarkus for native image compilation? Good luck with OCP certification!