Open-source alternatives to Openj9

TinyVM is a small, fast, lightweight virtual machine written in pure ANSI C.

MicroPython is a lean implementation of Python 3 optimized to run on microcontrollers and other resource-constrained systems. It serves as a cross-platform embedded runtime and hardware abstraction layer, providing a firmware framework that maps high-level software commands to specific microcontroller registers across diverse processor architectures. The project functions as an embedded language interpreter that enables rapid prototyping on hardware through an interactive read-eval-print loop. It supports a wide range of target environments, including ARM, ESP32, STM32, RISC-V, and WebAssembl

Microsoft Build of OpenJDK

Website - Developer Guide - Changelog - RoboPods - dkimitsa's dev blog

GraalVM is a polyglot virtual machine and high-performance runtime designed to execute multiple programming languages within a single environment. It functions as a JVM language toolkit for building language implementations, a native image compiler for transforming bytecode into standalone binaries, and an execution environment for LLVM bitcode and WebAssembly modules. The project is distinguished by its polyglot interoperability framework, which allows different languages to share data and execution state with low overhead. It utilizes self-modifying abstract syntax trees to optimize languag

PeachPie - the PHP compiler and runtime for .NET and .NET Core

doppio: A JVM in TypeScript v0.5.0

Avian - A lightweight Java Virtual Machine (JVM)

"interesting" VM in C. Let's see how this goes.

This project is a customized OpenJDK distribution optimized for high-throughput distributed applications. It features a coroutine runtime engine that replaces kernel threads with lightweight symmetric coroutines to increase concurrency and reduce scheduling overhead while maintaining standard Java interface compatibility. The runtime distinguishes itself through a multi-tenant resource manager and specialized networking providers. It implements resource isolation for CPU and memory to prevent cross-tenant interference and integrates Remote Direct Memory Access for high-throughput, low-latency

A JVM written in Go.

HHVM is a high-performance execution engine and runtime environment designed for the Hack language. It functions as a persistent web application server that processes incoming network traffic, while also providing command-line utilities for executing standalone scripts and performing automated tasks. The project distinguishes itself through a sophisticated execution model that utilizes just-in-time compilation to translate bytecode into optimized machine code. This process is supported by a static type analysis engine that enforces strict data constraints and identifies type inconsistencies b