Spring / Spring Boot 4 Basics Interview Questions
What is Spring Boot 4 and when was it released?
Spring Boot 4.0 was released on November 20, 2025, making it the most structurally significant Spring release since the move to Jakarta EE in Spring Boot 3.0 (2022). Spring Boot 4.1 followed on June 10, 2026 and is the current recommended version for new projects.
Spring Boot 4 is described by the Spring team as the beginning of a new generation -- not an incremental update but a genuine architectural shift built on top of Spring Framework 7 and Jakarta EE 11.
| Property | Detail |
|---|---|
| GA release | November 20, 2025 (4.0.0) |
| Latest stable | 4.1.0 (June 10, 2026) |
| Underlying framework | Spring Framework 7 |
| Jakarta EE baseline | Jakarta EE 11 (Servlet 6.1, Persistence 3.2, Validation 3.1) |
| Minimum Java | Java 17 |
| First-class Java support | Java 25 |
| Minimum Kotlin | Kotlin 2.2 |
| Recommended for new projects | Spring Boot 4.1 |
Key headlines:
- Complete modularisation into 70+ focused JARs
- Native API versioning in Spring MVC and WebFlux
- JSpecify null safety across the entire portfolio
- Jackson 3 is the new JSON library (Jackson 2 removed)
- JUnit 4 removed entirely
- Undertow removed (no Servlet 6.1 support)
- Built-in retry and concurrency limits via @Retryable and @ConcurrencyLimit
When was Spring Boot 4.0 released as GA?
Which underlying framework version does Spring Boot 4 build on?
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