Micronaut

Micronaut is a JVM framework governed by the Micronaut Foundation, with corporate and community sponsorship, a published roadmap, security announcements, commercial and community support options and a podcast. Its defining characteristic is performing dependency injection at compile time rather than at runtime.

Moving injection to compile time is a genuine architectural difference rather than an optimisation. Traditional JVM frameworks inspect classes through reflection when an application starts, which costs time and memory proportional to the size of the application. Resolving those relationships during compilation means startup is fast and memory use is low regardless of application size, and it also means errors that would have appeared at startup appear during the build.

That matters most where applications start frequently. Serverless functions are charged for cold start time, and a container that scales to zero pays startup cost on every scale-up, so a framework that starts in milliseconds changes what deployment models are viable.

Being run by a foundation with published sponsorship is worth noting when choosing. It means governance does not sit with one company, which is a consideration for a framework an organisation expects to depend on for years.