Open-source alternatives to Mezzano

xv6 is a Unix-like educational operating system designed for teaching kernel concepts. It is implemented as an instructional kernel for x86 and RISC-V architectures, featuring a virtual memory manager and support for symmetric multiprocessing. The system is designed to demonstrate core OS principles through a simplified re-implementation of Unix Version 6. It provides a controlled environment for studying system calls, trap handling, and process lifecycles. Its capability surface covers process management, including scheduling and context switching, and memory management via page tables for

This project is a technical reference and educational guide focused on the internal architecture of the Linux kernel. It serves as a low-level systems programming resource and documentation for operating system internals, detailing the implementation of core mechanisms within the kernel source code. The materials provide a detailed study of the Linux kernel, tracing behavior through actual C source and assembly. It specifically covers the progression from the bootloader and decompression to the final kernel entry point, alongside the management of hardware interrupts and symmetric multiproces

ToaruOS is an independent operating system built from the ground up without external dependencies. It features a custom x86-64 kernel that supports symmetric multiprocessing and paging, paired with a graphical windowing system and a dedicated bytecode interpreter for application logic. The system distinguishes itself by integrating an embedded Python environment for system-level development and a custom graphical interface that handles its own window composition and text rendering. It includes a compatibility layer for third-party application support and a system package manager for handling

rpi4-osdev is a project for bare metal operating system development targeting the Raspberry Pi 4. It focuses on creating a custom operating system that runs directly on the hardware without an underlying kernel or abstraction layer. The project provides a codebase and instructional guide for developing a low-level system from scratch. This process involves transitioning from early boot code to kernel execution on the ARM64 architecture. The technical scope covers embedded system bootstrapping and low-level hardware interfacing. This includes managing memory-mapped I/O, physical address mappi

Asterinas is a memory-safe operating system kernel designed to prevent data races and memory corruption. It functions as a Linux-ABI compatible kernel, enabling the execution of existing Linux binaries and container workloads while providing a declarative operating system distribution model. The project distinguishes itself by acting as a virtual machine container host and a confidential computing guest OS, allowing it to run within hardware-isolated Trusted Execution Environments such as Intel TDX. It implements a minimal trusted computing base by isolating unsafe low-level operations and se

OSV is a unikernel operating system and cloud-native execution environment designed to run as a secure microVM on hypervisors such as KVM, Firecracker, Xen, and VMware. It functions as a Linux binary compatible runtime, allowing unmodified Linux binaries to be executed as secure microVMs without requiring recompilation. The project distinguishes itself through its ability to package applications into minimal bootable images and its provide of a virtual machine management API. This REST interface enables remote monitoring of system health, management of execution traces, and control over guest

NuttX is a POSIX-compliant real-time operating system designed for microcontrollers ranging from 8-bit to 64-bit architectures. It provides a deterministic execution environment with a real-time task scheduler and a POSIX embedded kernel to ensure portable code execution across diverse hardware targets. The project distinguishes itself through a comprehensive hardware abstraction layer that provides standardized drivers for I2C, SPI, CAN, and USB across various semiconductor chipsets. It also features an embedded networking stack supporting TCP, UDP, IPv4, and IPv6, alongside industrial proto

TinyGo is a specialized compiler and development toolkit designed to bring the Go programming language to resource-constrained microcontrollers and WebAssembly environments. It provides a bare-metal runtime environment that enables high-level code execution without the need for a traditional operating system, utilizing an LLVM-based backend to generate efficient machine instructions. The project distinguishes itself through aggressive optimization techniques tailored for small hardware, including a static memory allocation strategy and whole-program dead code elimination that significantly re

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

smoltcp is a standalone TCP/IP network stack written in Rust, designed specifically for bare-metal and embedded systems. It provides a memory-safe implementation of the internet protocol suite that operates without requiring dynamic heap allocation. The project is distinguished by its heap-less memory management, using fixed-size buffers and manually allocated memory to ensure deterministic performance. It employs zero-copy packet processing and an interface-based hardware abstraction to decouple the network stack from physical hardware. The stack covers a broad range of networking capabilit

BLAKE3 is a high-performance implementation of the BLAKE3 cryptographic hash algorithm used for calculating secure data digests and fingerprints. It functions as a parallel cryptographic hash tool that distributes workloads across multiple processor threads to process large datasets rapidly. The project provides specialized tools for keyed hashing and the generation of message authentication codes. It also includes functionality for cryptographic key derivation, allowing the creation of unique secret sub-keys from a master key and context strings. The implementation supports data integrity v

Limine is a multiprotocol operating system bootloader that bridges low-level hardware initialization and system software across legacy BIOS and modern UEFI firmware environments. It executes directly on bare-metal hardware without an underlying operating system kernel or standard C library, parsing storage media and filesystems during the early boot sequence before OS drivers load. The software targets diverse processor architectures including x86, ARM, RISC-V, and LoongArch through discrete target binaries built from shared source code. It reads files directly from FAT and ISO9660 storage f

Kernel is an educational hobby operating system and low-level systems programming project written in Rust. Designed for students and hobbyists, the project provides a minimalist environment to explore computer architecture, CPU design, and kernel development directly on hardware without relying on a standard library or underlying operating system. The implementation features a freestanding language runtime and a custom target specification that replaces standard library components for bare-metal execution. It includes a multiboot bootloader interface to parse early-boot hardware handoff stat

ISPC is a vectorizing compiler and SIMD parallel programming language that implements a single program multiple data model. It serves as a toolchain for translating C-based code with parallel extensions into optimized machine code for various CPU and GPU architectures using an LLVM backend. The compiler is designed for cross-platform SIMD toolchain support, generating specialized instruction sets for x86 SSE/AVX, ARM NEON, and Intel GPU from a single source. It features a runtime dispatch mechanism that selects the most efficient hardware-specific implementation for the current system during

This project is a comprehensive performance programming guide and reference for the Go language, focusing on runtime efficiency and memory optimization. It provides a collection of patterns and techniques designed to increase execution speed by reducing garbage collection overhead and optimizing memory usage. The resource distinguishes itself through detailed reference implementations for memory optimization, such as escape analysis, object pooling, and structure memory alignment. It offers specific strategies for reducing binary size and improving CPU cache efficiency through structure memor

LiteX is an FPGA SoC development suite and SoC builder framework used to programmatically design system-on-chips. It provides a hardware description toolchain that uses a scriptable framework to define hardware layouts and automate the generation of hardware description language code. The project distinguishes itself by orchestrating multiple vendor and open-source toolchains to synthesize digital logic and generate deployable bitstreams. It supports multi-language logic integration, allowing disparate hardware description languages to be combined into a single project. The framework covers

oneAPI Threading Building Blocks (oneTBB)

MetalLB is a Kubernetes load balancer implementation and IP address manager designed for bare metal clusters. It functions as a networking tool that provides external connectivity and traffic distribution by assigning external IPv4 and IPv6 addresses to services. The project differentiates itself by providing two distinct advertisement modes. It can operate as a BGP routing controller, using the Border Gateway Protocol to announce service IPs to external routers with support for bidirectional forwarding detection and VRF-aware routing. Alternatively, it can act as a Layer 2 network advertiser

This project is a Chinese translation and educational resource focused on the internal workings of the Linux kernel. It provides a curated collection of technical content designed for studying low-level operating system mechanisms and kernel development. The project utilizes a specialized localization workflow where translations are maintained in a forked repository. It employs a patch-based model and Git-driven synchronization to align Chinese translations with the original English source files through differential merge processes. The technical scope covers core operating system internals,

AltSnap is a window manager utility and layout system that organizes application windows using custom snap grids and mouse-driven resizing and movement. It functions as a low-level input hook that intercepts keyboard and mouse events at the OS level to trigger custom window management actions. The project includes a coordinate-based grid mapper for precise snapping to custom zones and an input remapper that assigns keyboard scan codes to virtual mouse buttons. It also features a window automation CLI used to trigger management tasks on foreground or targeted application windows. The tool pro

This repository provides configuration sets for the Quantumult X network proxy client. It consists of routing rules, policy groups, and script rewrites designed to manage network connectivity and automation. The project features a network traffic router that uses rules and regular expressions to direct traffic toward specific proxy servers based on destination. It includes an HTTP request rewriter to modify network requests and responses to customize application behavior or bypass restrictions. The configuration covers automated task scripts for the maintenance of external web services, regi

chadwm is a tiling window manager for X11 written in C. It organizes application windows using dynamic tiling layouts and automated arrangement patterns to manage screen real estate. The project utilizes a patch-based extension system to integrate specific behaviors, such as Fibonacci tiling and vanity gaps. It employs a tagging system for workspace organization, allowing windows to be segmented into virtual desktops. The environment includes a modular widget framework for monitoring system metrics and hardware controls, alongside centralized configuration files for managing visual themes an

Pixi.js is a high-performance 2D graphics engine used to render interactive animations, sprites, and visual effects in web browsers. It functions as a WebGL 2D rendering engine and HTML5 graphics library designed to produce high-performance two-dimensional visuals. The project operates as a 2D sprite framework and a web-based visual effects engine, providing tools to apply filters, blend modes, and masks to real-time graphics. It also serves as an interactive web canvas API for handling multi-touch and mouse input to build responsive graphical user interfaces. The framework covers a broad se

Awesome is a programmable tiling window manager for the X11 Window System. It functions as a dynamic window manager that automatically arranges application windows into non-overlapping tiles based on predefined layout rules to maximize screen space. The project provides a scriptable desktop environment where system behaviors and layouts are defined through an embedded Lua interpreter. This allows for the creation of a personalized interface and a keyboard-driven workflow for managing application windows. The system covers dynamic window layout management and the configuration of system behav

Karing is a multi-protocol proxy client and network traffic router designed to manage and direct internet traffic through various proxy protocols. It functions as a proxy subscription manager that imports and converts server lists from multiple external formats and providers into a unified configuration. The project features a cross-device synchronization system that keeps network routing settings and server lists consistent across multiple devices via cloud or local sharing. It includes a latency-based server selector that measures real-time response times to automatically connect to the fas

This project is a technical guide and implementation library for advanced visual effects and hardware-accelerated animations using the Core Animation framework on iOS. It provides a comprehensive reference for creating high-performance motion graphics, custom graphic rendering, and the construction of 3D engines using perspective transforms and Z-axis manipulation. The collection distinguishes itself through a deep focus on GPU rendering optimization and graphics performance. It covers advanced strategies to maintain high frame rates, such as reducing offscreen rendering via shadow path optim

Surge is a network traffic routing and configuration system designed to categorize and steer network requests using curated rule sets, domain lists, and IP databases. It provides the data structures and filtering logic necessary to manage how application traffic is directed across proxies, direct connections, or regional gateways. The project distinguishes itself through granular traffic identification and steering. It identifies network requests by matching them against system process names, user-agent strings, and geographic IP ranges to apply specific routing policies. This allows for the