Kaffe
Kaffe is a discontinued "clean room design" version of a Java Virtual Machine. It comes with a subset of the Java Platform, Standard Edition, Java API, and tools needed to provide a Java runtime environment. Like most other Free Java virtual machines, Kaffe uses GNU Classpath as its class library.
Initially developed as part of another project, developers Tim Wilkinson and Peter Mehlitz founded Transvirtual Technologies, Inc. with Kaffe as the company's flagship product. In July 1998, Transvirtual released Kaffe OpenVM under a GNU General Public License.
When compared to the reference implementation of the Java Virtual Machine written by Sun Microsystems. It comes with just-in-time compilers for many of the CPU architectures, and has been ported to more than 70 system platforms in total.
Unlike other implementations, in the past Kaffe used GNU Multi-Precision Library to support arbitrary precision arithmetic. This feature has been removed from release 1.1.9. The capability was removed to reduce the maintenance work, expecting that interested people will integrate GMP support into GNU Classpath or OpenJDK. Subsequently, GNU Classpath introduced GMP support in version 0.98.