List of Java virtual machines

Free and open source implementations

Active

• Azul Zulu — is an OpenJDK build supported by Azul Systems and is compliant with the Java SE 11, 8, 7, and 6 standards.
• Codename One — uses the open source ParparVM
• Eclipse OpenJ9 — from IBM, for Windows, AIX, Linux, macOS, MVS, OS/400, Pocket PC, z/OS.
• GraalVM — is based on HotSpot/OpenJDK, it has a polyglot feature, to transparently mix and match supported languages.
• HotSpot — the open-source Java VM implementation by Oracle.
• JamVM — developed to be an extremely small virtual machine compared to others. Designed to use GNU Classpath. Supports several architectures. GPL.
• Jikes RVM — research project. PPC and IA-32. Supports Apache Harmony and GNU Classpath libraries. Eclipse Public License.
• leJOS — Robotics suite, a firmware replacement for Lego Mindstorms programmable bricks, provides a Java programming environment for the Lego Mindstorms RCX and NXT robots.
• Maxine — meta-circular open source research VM from Oracle Labs and the University of Manchester.

  Inactive

• Apache Harmony — supports several architectures and systems. Discontinued November 2011. Apache License 2.0.
• GCJ the GCC Java compiler, that compiles either to bytecode or to native machine code. As of GCC 7, gcj and associated libjava runtime library have been removed from GCC.
• IKVM.NET — Java for Mono and the Microsoft.NET Framework. Uses OpenJDK. Zlib License.
• JOP — hardware implementation of the JVM. GPL 3.
• Juice — JavaME experimental JVM developed to run on the NUXI operating system.
• Jupiter — uses Boehm garbage collector and GNU Classpath. GPL. Unmaintained.
• Kaffe — uses GNU Classpath. GPL. 1.1.9 released on February 26, 2008.
• Mika VM — intended for use in embedded devices. Cross-platform. BSD-style licence.
• NanoVM — developed to run on the Atmel AVR ATmega8 used in the Asuro Robot, can be ported to other AVR-based systems.
• SableVM — first free software JVM to support JVDMI and JDWP. Makes use of GNU Classpath. LGPL. Version 1.13 released on March 30, 2007.
• Squawk virtual machine — a Java ME VM for embedded systems and small devices. Cross-Platform. GPL.
• SuperWaba — Java-like virtual machine for portable devices. GPL. Discontinued, succeeded by TotalCross.
• TakaTuka — for wireless sensor network devices. GPL.
• TinyVM.
• VMKit of LLVM.
• Wonka VM — developed to run on Acunia's ARM-based hardware. Some code drawn from GNU Classpath. BSD-style licence. No longer under active development, superseded by Mika VM.

  Java operating systems

• JX Java operating system that focuses on a flexible and robust operating system architecture developed as an open source system by the University of Erlangen. GPL. Version 0.1.1 released on October 10, 2007
• JavaOS - Original project from Sun Microsystems
• PreonVM — a bare metal Java VM for embedded systems.

  Proprietary implementations

Active

• Azul Zing JVM — a full compliant Java Virtual Machine based on OpenJDK that uses Azul Systems's C4 garbage collector.
• JamaicaVM — a hard real-time Java VM for embedded systems.

  Inactive

• Excelsior JET — a licensed Java SE implementation with AOT compiler for Windows, OS X, and Linux on Intel x86 and Linux on 32-bit ARM.
• Jinitiator — developed by Oracle before they purchased Sun. Designed to improve support for Oracle Forms in web sites.
• JRockit — acquired by Oracle for Linux, Windows and Solaris.
• Mac OS Runtime for Java.
• Microsoft Java Virtual Machine — discontinued in 2001.

  Lesser-known proprietary Java virtual machines

• Blackdown Java was a licensed port to Linux of the reference SunSoft implementation. It was discontinued in 2007, after OpenJDK became available.
• Sun CVM — CVM originally standing for "Compact Java Virtual Machine".
• Gemstone — modified for Java EE features.
• Intent.
• PreonVM — a Java VM for embedded systems and small and resource constrained devices.