GraalVM

GraalVM is a Java runtime and toolchain from Oracle producing native executables that use a fraction of the memory and CPU a JVM requires, with Native Image, the Graal Dev Kit for Micronaut, GraalOS and polyglot runtimes GraalJS, GraalPy, GraalWasm and Espresso.

Ahead-of-time compilation is what makes GraalVM a different proposition from every other entry in this category rather than another build of the same thing. A native executable starts in milliseconds and holds a fraction of the memory, which changes where Java can be deployed: serverless functions and short-lived containers were effectively closed to a runtime that spends seconds warming up.

The trade is real and worth stating. Native Image compilation is slow, reflection and dynamic class loading need explicit configuration, and the resulting binary loses the just-in-time compiler's ability to optimise from observed behaviour, so long-running throughput-heavy services often perform better on a conventional JVM.

The polyglot runtimes are the more experimental half and should be treated as such, since running JavaScript, Python or WebAssembly inside the same process is powerful for embedding a scripting layer and carries compatibility limits against the reference implementations. GraalVM 25.3 adds priority inlining, vectorisation and control-flow integrity. It is free.