Operating systems
I love using macOS as my personal OS.
And I like NixOS and it's nix package manager.

Interesting OSes

    ​MirageOS - Library operating system that constructs unikernels. (Docs) (Docs code) (mirage-solo5) (The road ahead for MirageOS in 2021)
    ​DahliaOS - Modern, secure, lightweight and responsive operating system, combining the best of GNU/Linux and Fuchsia OS. (GitHub) (HN) (Pangolin Desktop UI) (ISO releases)
    ​Redox - Unix-like Operating System written in Rust. (Web)
    ​Toddler - Well-designed usable and portable microkernel OS.
    ​OS67 - Unix-like toy kernel.
    ​SerenityOS - Graphical Unix-like operating system for x86 computers. (Web) (Year 3 in review) (HN)
    ​Resea - Pure microkernel-based hackable operating system written from scratch in C and Rust.
    ​Rux - Hobbyist microkernel written in Rust, featuring a capability-based system similar to seL4.
    ​redshirt - Experiment to build some kind of operating-system-like environment where executables are all in WASM and are loaded from an IPFS-like decentralized network.
    ​Spectrum OS - Declarative, reproducible, compartmentalized Linux. (Developer manual) (Discussions) (HN)
    ​mikado - RISC-V Experimental OS.
    ​mkernel - Minimalist kernel which prints "my first kernel" on the screen and then hangs. (HN)
    ​Barebones - Barebones multiboot kernel for beginners.
    ​xv6 - Re-implementation of Dennis Ritchie's and Ken Thompson's simple, Unix-like teaching operating system. (PDF) (HN) (HN 2) (Lobsters)
    ​xv6 for RISC-V​
    ​Orange Slice - Research kernel and hypervisor attempting to get fully deterministic emulation with minimum performance cost.
    ​Cloud Hypervisor - Open source Virtual Machine Monitor (VMM) that runs on top of KVM.
    ​RancherOS - Tiny Linux distro that runs the entire OS as Docker containers.
    ​Bottlerocket OS - Free and open-source Linux-based operating system meant for hosting containers.
    ​XNU kernel - Part of the Darwin operating system for use in macOS and iOS operating systems.
    ​Haiku - Open-source operating system that specifically targets personal computing. (HN) (Haiku Community)
    ​Pebble - Microkernel and userspace written in Rust, with first-class message passing.
    ​RustyHermit - Rust-based, lightweight unikernel.
    ​Distaff - Zero-knowledge virtual machine written in Rust.
    ​zCore - Reimplement Zircon microkernel in Rust.
    ​lilith - POSIX-like x86-64 kernel and userspace written in Crystal.
    ​Genode - Operating System Framework.
    ​Shrine - TempleOS distro for heretics.
    ​Subgraph OS - Desktop computing and communications platform that is designed to be resistant to network-borne exploit and malware attacks. (Handbook)
    ​Mezzano - Operating system written in Common Lisp. (HN)
    ​Collapse OS - Bootstrap post-collapse technology. (HN)
    ​LegoOS - Disseminated, Distributed OS for Hardware Resource Disaggregation.
    ​CuBitOS - General-purpose, formally-verified, 64-bit operating system in SPARK/Ada for x86-64.
    ​Demikernel - Library operating system architecture designed for use with kernel-bypass I/O devices.
    ​Drone - Embedded Operating System for writing real-time applications in Rust. (drone-core)
    ​Manticore - Research operating system, written in Rust. (Web)
    ​CyanOS - x86 monolithic kernel operating system, coded in C++ 17 and few lines of x86 Assembly.
    ​ChaiOS - Modular multi-platform hobby OS. Hybrid kernel, largely monolithic. Kernel C library is dynamically linked.
    ​Tails - Portable operating system that protects against surveillance and censorship. (Intro)
    ​EmuTOS - Free operating system for Atari ST computers, and more. (Web)
    ​HalideOS - Experimental operating system written entirely from scratch. It supports a basic shell with some commands including a command line calculator.
    ​Biscuit - Monolithic, POSIX-subset operating system kernel in Go. (HN) (Code)
    ​illumos - Unix operating system which provides next-generation features for downstream distributions, including advanced system debugging, next generation filesystem, networking, and virtualization options. (Rise and Development of illumos)
    ​Managarm - Pragmatic microkernel-based OS with fully asynchronous I/O. (Fully Asynchronous OS Based on Modern C++ - Alexander Grinten (2020))
    ​EggOS - Go unikernel running on x86 bare metal. (HN)
    ​KnightOS - Third-party operating system for TI calculators.
    ​eduOS-rs - Teaching operating system written in Rust. (Web)
    ​Stupid Operating System - Simple, tiny toy OS implemented in Rust.
    ​Theseus OS - New OS written from scratch in Rust to experiment with novel OS structure, better state management, and how to shift OS responsibilities like resource management into the compiler. (HN)
    ​TempleOS - Talk to God on up to 64 cores. (Web) (TempleOS on real hardware)
    ​CactusOS - Simple operating system that is aimed to not be anything like linux.
    ​Zephyr - New generation, scalable, optimized, secure RTOS for multiple hardware architectures. (Docs)
    ​Cosmos - Operating system "construction kit". Build your own OS using managed languages such as C#, VB.NET, and more. (Web)
    ​MollenOS - Modern operating system that is built with focus on abstraction and a modular design.
    ​Azure RTOS ThreadX - Advanced real-time operating system (RTOS) is designed specifically for deeply embedded applications.
    ​HelenOS - Portable microkernel-based multiserver operating system written from scratch. (Web)
    ​bootloader - Experimental x86 bootloader written in Rust and inline assembly.
    ​Cyjon - Simple, clean, multi-tasking operating system written in pure assembly language for 64-bit processors from the AMD64 family.
    ​Contiki - Open source operating system that runs on tiny low-power microcontrollers.
    ​OSv - Modular unikernel designed to run applications securely on micro-VMs . (Code) (HN) (HN 2)
    ​Rumprun - Uses rump kernels to provide the Rumprun unikernel. Rumprun works on not only on hypervisors such as KVM and Xen, but also on bare metal.
    ​Rump Kernels - Enable you to build the software stack you need without forcing you to reinvent the wheels.
    ​mOS - Unix-like operating system developed from scratch and aims to POSIX compliant.
    ​pdp7-unix - Project to resurrect Unix on the PDP-7 from a scan of the original assembly code.
    ​core-os-riscv - xv6-like operating system on RISC-V with multi-core support.
    ​rCore - Rust version of THU uCore OS. Linux compatible.
    ​Eltanin - Free, simple, and complete general-purpose operating system.
    ​skiftOS - Simple, handmade, operating system with a graphical user interface. (Web)
    ​ChrysaLisp - Parallel OS, with GUI, Terminal, OO Assembler, Class libraries, C-Script compiler, Lisp interpreter and more. (HN)
    ​Pluto - x86 kernel written in Zig.
    ​LeOS Kernel - Kernel project for operating system for ARM 64bit (AArch64) written in Rust. (Web)
    ​RustyHermit - Rust-based, lightweight unikernel. (Article)
    ​Jehanne - Simple operating system. (Web)
    ​Mimosa - Operating system consists of a minimal kernel built on C++ and Scheme.
    ​daintree - ARMv8-A operating system, plus a UEFI bootloader, all written in Zig.
    ​AROS - Lightweight, efficient, and flexible desktop operating system. (HN)
    ​M3 - Microkernel-based system for heterogeneous manycores.
    ​vanadinite - RISC-V OS written in Rust.
    ​Tetris-OS - Operating system that only plays Tetris. (HN) (Video)
    ​Helium - BSD-based OS project that aims to provide an experience like and some compatibility with macOS.
    ​Harvey - Distributed operating system. (Web)
    ​TypOS - Operating system for typechecking processes.
    ​KolibriOS - Tiny yet incredibly powerful and fast operating system. (HN)
    ​Kerla - New operating system kernel with Linux binary compatibility written in Rust.
    ​rustboot - Tiny 32 bit kernel written in Rust.
    ​mycelium - Hobby OS in Rust.
    ​WINIX OS - UNIX-style Operating System for the Waikato RISC Architecture Microprocessor. (HN)
    ​Aquila OS - Complete Operating System (kernel + system) that is designed to be POSIX compliant and mostly ISA transparent. (Web)
    ​FuzixOS - Because Small Is Beautiful.
    ​Mongoose - Small toy OS with no memory protection. (Lobsters)
    ​Node Replicated Kernel - Research OS kernel for x86-64 (amd64) machines written in rust. (Web) (Book)
    ​Multics - Pioneering operating system, commonly considered the "progenitor" of the UNIX operating system. (Code)
    ​Tilck - Tiny Linux-Compatible Kernel.
    ​Airyx OS - BSD-based OS project that aims to provide an experience like and some compatibility with macOS. (Code) (HN) (Lobsters) (HN)
    ​Lemon OS - UNIX-like 64-bit operating system written in C++. (Code)
    ​Pumpkin OS - x64 port/re-implementation of PalmOS. (Lobsters)
    ​SteinsOS - Operating system featuring non-preemptive single-threaded kernel targeting on armv8.
    ​EmbassyOS - Graphical operating system for running self-hosted software. (Web)
    ​Singularity - Microsoft’s Experimental OS. (HN)