Spring Boot vs Quarkus vs Micronaut: Startup, Native Images, Ecosystem, Support and Which to Choose

The short answer

Stay with Spring Boot unless startup time and memory per instance are a real constraint, because its family of integrated projects is the broadest in Java and rewriting working code rarely pays for itself. Choose Quarkus for new services built for Kubernetes and native executables, especially if your team knows Jakarta EE and MicroProfile. Choose Micronaut when you want compile-time dependency injection with a programming model that feels close to Spring. All three are Apache 2.0, all three can build GraalVM native executables, and all three run well on the JVM. The difference is how much work each does when the application starts versus when it is built, and how much existing Spring code you would have to change.

Spring Boot vs Quarkus vs Micronaut at a glance

Spring Boot: the default, now with build-time options

Spring Boot exists to make stand-alone, production-grade Spring applications that you can just run. On the JVM it reads your configuration classes and builds the application context when the application starts, which is flexible: profiles, conditional beans and property switches can change what gets created at runtime. That flexibility costs startup time and memory, which matters little for a service that runs for weeks and a lot for one that scales from zero.

For those cases Spring Boot supports GraalVM native images through ahead-of-time processing. Spring's own documentation lists the trade-offs: the application is analysed statically at build time, the classpath is fixed, beans cannot change at runtime, and features such as @Profile and @ConditionalOnProperty are restricted. In return you get a platform-specific executable with faster startup and a smaller memory footprint.

Spring Boot's open source support is short per minor line. On spring.io's schedule, 3.5.x open source support ended on 30 June 2026, 4.0.x ends on 31 December 2026, and 4.1.x, released on 30 June 2026, runs to 31 July 2027. Our Spring support calendar tracks every line.

Quarkus: built for containers from the start

Quarkus calls itself Kubernetes-native and moves framework work into the build phase to cut what happens at runtime. Its dependency injection, ArC, is based on Jakarta CDI and resolved at build time. It integrates with Jakarta EE and MicroProfile standards, supports imperative and reactive code, and has a dev mode with live reload. Native executables build with GraalVM or Mandrel, a downstream distribution of GraalVM CE aimed at Quarkus, and can be built inside a container without a local GraalVM.

Quarkus releases a new minor roughly every month and designates an LTS every six months, supported for twelve months. Releases on 30 September 2026 included 3.40.1 and maintenance releases on the 3.33 and 3.27 lines, and 4.0.0.Beta1 followed on 1 October.

Quarkus offers Spring compatibility extensions, but they are a translation layer, not Spring. Its Spring DI guide is explicit: Spring annotations are read as metadata, the Spring application context is never started, Spring infrastructure classes do not run, and features such as @Conditional are not supported. Simple Spring code ports with little change. Code that relies on Spring's runtime machinery does not.

Micronaut: compile-time injection with a familiar feel

Micronaut describes itself as a modern, JVM-based framework with compile-time dependency injection. The compiler resolves the dependency graph, so wiring mistakes fail the build, and there is no classpath scanning or reflection at startup. It supports Java, Kotlin and Groovy, builds GraalVM native images, and ships modules for the major clouds and Kubernetes. Micronaut 5.2 is the current platform line, and 4.10 still received a release on 30 September 2026.

Performance

The three projects publish their own startup and memory figures, and each picks tests that suit it. The architecture explains the general pattern. Frameworks that resolve injection and configuration at build time, Quarkus and Micronaut by default and Spring Boot with AOT, start faster and use less memory, and the gap is widest for native executables. For long-running services on the JVM, startup matters less and throughput depends mostly on your code, your libraries and the JVM itself. Measure your own service in the deployment model you will use.

How to choose

• Stay on Spring Boot when you have existing Spring applications, rely on Spring Data, Spring Security or Spring Cloud, or want Spring's wider family of projects and integrations. Use Spring AOT and native images for the services where startup really matters.
• Choose Quarkus for new Kubernetes or serverless services where fast scale-up and memory density matter, and for teams already fluent in Jakarta EE and MicroProfile.
• Choose Micronaut when you want build-time injection with compile errors for wiring mistakes, or Kotlin and Groovy alongside Java.

Rewriting a working Spring estate to gain startup time is rarely worth it on its own. The more common pressure is the support calendar: Spring Boot minor lines leave open source support quickly, and estates still on 2.x face a Jakarta migration before they can move to 3 or 4. Our Spring Boot 2 to 3 migration guide covers that path.

Where OSSeva fits

OSSeva supports Spring, not Quarkus or Micronaut. OSSeva for Spring Boot ships CVE-patched Spring Boot 2.6 and 2.7 builds without a forced Spring 6 upgrade, patches the 3.x lines after their open source end dates, and covers 4.0 and 4.1, together with Spring Framework and Spring Security. It is priced per application, not per developer seat or deployment unit. If you are weighing a framework change because a Spring line is running out of support, patched builds give you time to decide on engineering grounds. See Spring continuation and Spring end-of-life support providers, or book a discovery call for a quote.

Frequently asked questions

Spring Boot vs Quarkus vs Micronaut: which is best?

Spring Boot for ecosystem breadth and existing Spring code. Quarkus for container-first services built on Jakarta EE and MicroProfile. Micronaut for compile-time injection with Java, Kotlin or Groovy. All three are mature and Apache 2.0 licensed; pick on your team's skills and deployment model.

Spring Boot vs Quarkus performance: which is faster?

Quarkus does more work at build time, so it usually starts faster and uses less memory, especially as a native executable. Spring Boot narrows the gap with AOT and native images. For long-running JVM services, request throughput depends more on your code than on the framework, so benchmark your own service.

Spring Boot vs Micronaut: what is the difference?

Spring Boot builds its application context at startup by default and offers AOT processing for native images. Micronaut resolves dependency injection at compile time, avoiding reflection and classpath scanning at startup. Spring Boot has the larger ecosystem; Micronaut catches wiring errors in the build.

Can Quarkus run Spring code?

Partly. Quarkus has Spring compatibility extensions that read Spring annotations for dependency injection, web and data access. The Spring application context never starts, though, so code that depends on Spring's runtime infrastructure, such as BeanPostProcessor or @Conditional, needs rewriting.

Is Quarkus replacing Spring Boot?

No. Both are actively developed. Quarkus is a strong choice for new cloud-native services, and Spring Boot keeps shipping a new minor line about every six months.

How long is a Spring Boot version supported?

Each minor line gets open source support for about 13 months. 4.0.x is supported to 31 December 2026 and 4.1.x to 31 July 2027. Commercial support from the Spring vendor and third-party patching extend that.