Open-source alternatives to Webvm

Phoenix is a comprehensive web development suite that provides a browser-based code editor, an AI-powered coding assistant, and a live web previewer. It integrates a visual Markdown document editor and a web-based Git client, allowing users to write and manage HTML, CSS, and JavaScript across different devices and platforms. The environment features a visual UI design system that maps canvas manipulations directly to code and enables in-place CSS editing. It supports real-time change previews and responsive layout testing across multiple device breakpoints to verify rendering on phones, table

Tart is an Apple Silicon virtualization manager used to build and run macOS and Linux virtual machines using native hardware virtualization frameworks. It functions as a virtual machine cluster orchestrator and an ephemeral runner for executing continuous integration pipeline steps within isolated, short-lived environments. The system utilizes an OCI-compatible virtual machine registry to push and pull images via standardized container registries. It features a controller-worker architecture that schedules virtual machine lifecycles across remote worker nodes, incorporating a secure SSH jump

Instantbox is infrastructure for managing isolated, containerized operating system environments. It deploys full Linux distributions as disposable instances that are accessible through a web-based terminal emulator. The system provides image-based provisioning via a catalog of supported Linux distributions. Each instance is assigned a unique URL for browser access and supports custom resource allocation for CPU and memory limits. Lifecycle management is handled through time-to-live settings that automatically prune expired containers to reclaim system resources. These capabilities support th

OSWorld is an evaluation framework and multimodal agent benchmark designed to test the ability of large language models to complete complex tasks within virtualized operating system environments. It provides a virtualized desktop sandbox and a virtual machine orchestrator to deploy, snapshot, and reset cloud-based desktops, ensuring reproducible test states for AI agent interactions. The system distinguishes itself by providing an OS-level action space that translates model decisions into mouse clicks, keyboard inputs, and system commands. It employs a standardized interface to integrate vari

Cloud Hypervisor is a Rust-based hypervisor and KVM virtual machine monitor designed to execute 64-bit guest operating systems. It functions as a user-space virtual machine manager that employs a minimal emulation layer to reduce memory overhead and latency for cloud workloads. The project distinguishes itself through the use of a memory-safe language to implement a virtio device emulator and a user-space device model. It provides a standardized web API for managing virtual machine lifecycles and resource configurations. The platform covers broad virtualization capabilities, including the em

LXD is a unified platform for managing both system containers and virtual machines through a single REST API and command-line interface. It provides a programmatic HTTP interface for controlling the full lifecycle of instances, enabling automation and integration with external tools. The system runs unprivileged containers with per-instance UID/GID mappings, seccomp filters, and AppArmor profiles for kernel-level isolation, while supporting multiple storage backends including directory, Btrfs, LVM, ZFS, Ceph, LINSTOR, and TrueNAS through a unified driver interface. The platform distinguishes

The solana-program-library is a blockchain system program suite providing a library of core blockchain operations and native functions implemented as reusable programs on Solana. It serves as a collection of smart contract templates and reference implementations for deploying verified programs to the Solana virtual machine. The project provides decentralized application infrastructure by offering standardized programs that act as foundational building blocks for applications. It focuses on the development and deployment of verified blockchain contracts to ensure consistent functionality acros

Hyperkit is a userspace virtual machine monitor and a development toolkit for building custom hypervisors. It provides primitives for embedding virtualization and hardware emulation capabilities directly into applications to execute guest operating systems within a userspace environment. The project features a guest operating system bootstrapping tool that loads kernels and initializes CPU states without relying on traditional firmware. It includes a hardware emulation library to create virtualized storage, serial ports, and networking components for guest system access. The system covers vi

86Box is a low-level x86 hardware emulator and vintage PC simulator designed to replicate early IBM PC compatibles. It provides virtualized environments for executing legacy operating systems, such as MS-DOS and early versions of Windows, by simulating processors and system designs ranging from the 8086 through the Pentium era. The project distinguishes itself through cycle-accurate processor simulation and high-fidelity hardware emulation. This includes the ability to route retro MIDI audio data to emulated hardware modules or external synthesizers to achieve authentic audio playback from le

LXD is a system container manager and virtual machine manager that provides a unified interface for running full Linux systems. It acts as a container cluster orchestrator, an image format converter, and an infrastructure manager that exposes control through a REST API and language-specific SDKs. The project distinguishes itself by providing a unified container and virtual machine abstraction, treating both as generic instances within a single management layer. It supports distributed cluster coordination to synchronize state and distribute workloads across multiple physical nodes. The syste

seL4 is a formally verified microkernel whose C implementation is backed by machine-checked mathematical proofs of correctness, confidentiality, integrity, and availability. It enforces strict isolation between processes through hardware-enforced address space separation and a capability-based access control system, where each process holds explicit rights only to the resources it has been granted. The kernel exposes hardware resources through a minimal API of system calls that manage threads, address spaces, and inter-process communication, with synchronous IPC supporting sender-identifying b

Miasm is a Python reverse engineering framework designed for binary analysis, disassembly, and modification. It functions as a binary analysis framework that lifts machine code into an intermediate representation to enable platform-independent security research. The system operates as a binary emulation engine and modification toolkit, allowing for the execution of binary code in a virtual environment to track state changes without native hardware. It provides tools for binary patching to update and modify raw binary files across multiple CPU architectures and executable formats. The framewo

xv6-riscv is a simplified Unix-like teaching operating system designed for the study of kernel design and hardware interaction. It provides a low-level RISC-V kernel implementation that serves as a bootable system image for execution and debugging within a virtual machine or emulator. The project focuses on educational instruction regarding the RISC-V architecture. It enables the study of operating system concepts through a minimal kernel that implements process management and memory handling. The system covers core kernel operations including multiprocessor resource management and the imple

VirtualBuddy is a graphical user interface and manager for creating and running macOS virtual machines on Apple Silicon. It serves as an interface for the native Apple Virtualization Framework, allowing users to provision and boot guest operating systems on ARM-based hardware. The tool provides a dedicated environment for managing virtual machine administration and software compatibility testing across different macOS versions. It enables the execution of guests via local files, remote URLs, or image catalogs, and supports booting into recovery mode for system repairs. The system covers hard

Wren is an embeddable, class-based scripting language and bytecode interpreter. It provides a dependency-free virtual machine designed for integrating dynamic script execution into host applications via a C API. The language is centered on a modern object-oriented model featuring inheritance, method overloading, and first-class functions. It utilizes a concurrent fiber runtime to manage lightweight, cooperatively scheduled execution paths without relying on operating system threads. The project includes a comprehensive suite of object-oriented primitives, closure-based state capture, and a m

This project is a front-end education portal and static website that serves as a repository for web development courseware. It provides instructional materials and source code for learning the fundamentals of HTML, CSS, and JavaScript. The site functions as a resource for students to practice programming skills through guided exercises and downloadable learning assets. It distributes educational content including instructional PDFs and exercise code to facilitate the study of front-end web development. The platform covers a variety of capabilities, including the integration of multimedia con

TeaVM is a Java bytecode transpiler and browser-based JVM runtime that converts compiled Java class files into JavaScript or WebAssembly. It functions as a compiler and build pipeline tool that enables applications written in various JVM languages to execute natively within a web browser. The project distinguishes itself by transforming bytecode directly into optimized web formats without requiring the original source code. It includes a WebAssembly bytecode compiler for high-performance execution and a specialized emulation system to handle asynchronous multithreading within the single-threa

The project is a web-based integrated development environment and online code execution platform built around the Monaco code editor. It provides a browser-based interface where users can write, edit, and execute source code across multiple programming languages without requiring local software installations. The application functions both as a standalone web interface and as an embeddable widget architecture. Through this component-based design, the editor and its dependencies can be mounted directly into external web pages to supply interactive programming environments and execution tools

UserScripts is a collection of JavaScript browser userscripts designed to modify website behavior and add custom functionality to web browsers. It serves as a multi-purpose toolset for web page content automation, web interface enhancement, and specialized web scraping and downloading. The project distinguishes itself through a wide range of specialized utilities, including a browser-based text transformer for character encoding and terminology mapping, and tools for bypassing content censorship. It provides advanced web scraping capabilities such as deciphering obfuscated download links, agg

Brain.js is a JavaScript neural network library for building, training, and running machine learning models in the browser or Node.js. It provides implementations for several network types, including feedforward networks, recurrent neural networks for time series forecasting, and autoencoders for data compression and denoising. The library features WebGL-based GPU acceleration to increase the speed of neural network computations on the graphics processor. It also includes a visualization tool that generates SVG images to represent the topology and layers of a feedforward network. The framewo

This project is a client-side tool that fetches a GitHub user’s entire contribution history and renders it as a single, continuous timeline chart. It operates entirely in the browser as a single-page application, using the HTML5 Canvas API to draw a pixel-level heatmap where color intensity reflects contribution frequency across every day from account creation to the present. The tool retrieves data through authenticated requests to the GitHub API, then aggregates daily counts into a date-range timeline without requiring any server-side processing. Its output serves as a comprehensive visual

chart.xkcd is a client-side JavaScript library used to generate data visualizations as scalable vector graphics directly in the browser. It functions as a graphing utility that manipulates DOM elements to produce various chart types without requiring server-side dependencies. The library is distinguished by a rendering engine that applies randomized stroke offsets and variable line weights to SVG paths. This process simulates a sketchy, hand-drawn aesthetic for data charts, creating a comic-like visual style. The project supports a variety of visualization formats, including bar, line, circu

Firefox is a cross-platform web browser engine designed to render web content, execute JavaScript, and manage secure browsing sessions. It utilizes a multi-process isolation architecture that distributes browser tasks across independent operating system processes to ensure stability and prevent site-specific failures from impacting the entire application. The engine incorporates a sandboxed execution environment to restrict web content and untrusted scripts to isolated memory compartments, enforcing security policies that prevent unauthorized access to system resources. The project distinguis

Magentic-UI is an agentic UI toolkit and framework that enables large language models to interface with real-time browser environments, operating systems, and virtual machines. It provides a sandbox environment where models can execute instructions to manage local files and run shell commands. The project functions as a web interaction orchestrator and browser automation framework, allowing for the execution of end-to-end web workflows and form completions. It coordinates these actions through a system that translates natural language goals into executable sequences. The toolkit covers sever

This project provides a functional package manager and a reproducible build system designed to ensure identical build inputs always produce the same outputs. It serves as the foundation for a declarative Linux distribution where the entire system state is defined in a configuration file, enabling predictable deployments and full-system rollbacks. The system uses a deterministic functional language and a lazy-evaluation expression engine to manage software dependencies and isolate build environments. It distinguishes itself through a content-addressable store that allows multiple versions of s

KubeVirt is a Kubernetes virtualization platform and cloud-native hypervisor manager. It provides a runtime environment that allows virtual machines to be defined, launched, and managed as declarative resources within a Kubernetes cluster, enabling them to run alongside containers on the same nodes. The system enables the hybridization of cloud infrastructure by combining traditional virtual machines with containerized workloads on a single shared platform. It supports the live migration of running virtual machines between physical hosts to facilitate cluster maintenance and load balancing.

AIOS is an LLM agent operating system and orchestration kernel designed to manage memory, resource scheduling, and tool execution for multiple autonomous AI agents. It serves as a comprehensive framework for developing and deploying agents, featuring a dedicated resource manager that coordinates model backends, GPU memory, and isolated kernel instances. The system distinguishes itself through a semantic memory engine that uses vector search and autonomous clustering for long-term knowledge management, and a semantic file system that allows users to control computer files and system operations