Kaffe is a GPLed alternative Java Runtime Environment with yet another coffee related name. It includes a JVM plus the base java class libraries. Interpreted Java is supported across a almost any platform, and Just-In-Time (JIT) compiling is supported over a wide array of architectures including Intel, Alpha, SPARC, and ARM.

A company called Transvirtual sponsers the development, and markets a related product called KaffePro. KaffePro is aimed at embedded applications.

Version 1.0.6 implements Java 1.1 with some Java 1.2 features.