When would you choose Micronaut over Spring Boot for a new project?

Micronaut tends to be the stronger choice when startup time and memory footprint directly affect cost or user experience: serverless functions billed per invocation, high-density container deployments where you're packing many small services per node, and CLI tools that need to start almost instantly.

It's also compelling when GraalVM native image is a hard requirement, since Micronaut's compile-time design avoids most of the reflection configuration headaches that come with retrofitting native image onto a reflection-heavy framework.

Spring Boot remains the safer default when the team already has deep Spring expertise, the project needs the breadth of Spring's ecosystem such as extensive third-party integrations, mature tooling, and a larger hiring pool, or the workload is a long-running service where a few extra seconds of JVM startup and higher idle memory don't materially matter.

In short, choose based on constraints: startup, memory, and native-image pressure favor Micronaut, while ecosystem breadth and team familiarity favor Spring Boot, rather than assuming one is universally "better."