Website

• os-dev - Wiki with everything you need to know
• Genodians - Stories around the Genode Operating System
• Lowlevel - A wiki about creating an OS from scratch. In German
• POSIX - Standards for maintaining compatibility between operating systems

Linux Kernel specific Resources

• OldLinux - A Heavily Commented Linux kernel source and more
• The Linux Kernel documentation
• Working with the kernel development community
• linux-insides
• Linux Kernel Workbook
• bootlins interactive Linux kernel map
• OldLinux - A Heavily Commented Linux kernel source and more

Online books

• Linux Kernel in a Nutshell - Covers the entire range of kernel tasks, available as chapters or one PDF
• The little book about OS development
• Operating System Development Series - OS from the ground up in C
• xv6: a simple, Unix-like teaching operating system - Book for Xv6

Tutorials

• Baking Pi – Operating Systems Development
• Bran's Kernel Development
• Roll your own toy UNIX-clone OS
• Writing an OS in Rust
• Making a RISC-V Operating System using Rust
• Operating systems development for Dummies
• Kernels 101 – Let’s write a Kernel
• Kernels 201 - Let’s write a Kernel with keyboard and screen support
• Writing a Bootloader

Papers

• The benefits and costs of writing a POSIX kernel in a high-level language
• Running Scheme On Bare Metal

Hobby

• KolibriOS - MenuetOS fork
• Brutal - org/brutal) - An operating system inspired by brutalist design that combines the ideals of UNIX from the 1970s with modern technology and engineering
• KripayaOS - x86 Kernel with it's own bootloader.
• LemonOS - OS) - UNIX-like 64-bit operating system written in C++.
• MenuetOS - Hobby OS supporting 32 and 64 bit, written in Assembly language
• MyXomycota - Monolithic kernel in C
• PathOS - Hobby OS based on [MikeOS](https://github.com/mig-hub/mikeOS), written in Assembly Language
• PonyOS - ToaruOS-based, My Little Pony themed OS
• Snowdrop OS - a homebrew operating system from scratch, in assembly language
• Sortix - Hobby OS in C and C++ by *Jonas 'Sortie' Termansen*
• TETRIS-OS - An operating system, but it only plays Tetris.
• Visopsys - Open Source Hobby OS developed since 1997
• Xv6 - A teaching operating system developed in the summer of 2006 for MIT's operating systems course
• BareMetal - 64 bit operating system written in Assembly for x86-64
• HalideOS - experimental operating system written entirely from scratch.

• ackOS - A simple 64-bit operating system.
• BoneOS - OS for everyone built by everyone
• Bottlerocket OS - Linux-based OS meant for hosting containers.
• eggos - A Go unikernel running on x86 bare metal
• gopher-os - A proof of concept OS kernel written in Go
• HelenOS - multikernel multiserver OS
• helium - A BSD-based OS project that aims to provide an experience like and some compatibility with macOS
• Interim - Minimalist OS with concepts from Lisp machines and Plan9
• Sculpt OS - Genode based OS
• AROS - Research Operating System is a lightweight, efficient, and flexible desktop operating system, designed to help you make the most of your computer. It's an independent, portable and free project, aiming at being compatible with AmigaOS at the API level
• Cadex OS - a simple operating system kernel originally made by Prof. Douglas Thain at the University of Notre Dame and students
• CollapseOS - Bootstrap post-collapse technology
• Embox - Configurable operating system kernel designed for resource constrained and embedded systems.
• Fiwix - A UNIX-like kernel for the i386 architecture.
• FreeRTOS - freertos) - IoT operating system for microcontrollers, by Amazon.
• Genode - A FOSS operating system framework consisting of a microkernel abstraction layer and a collection of userspace components
• GreenteaOS - A free OS designed to be compatible with Windows executables
• HarveyOS - A distributed operating system
• Hubris - Hubris is an operating system for microcontrollers developed by Oxide Computer Company in Rust
• Mimiker - Simple unix-like operating system for education and research purposes. MIPS microkernel.
• Sanos - Sanos is a minimalistic 32-bit x86 operating system kernel for network server appliances running on standard PC hardware.
• skiftOS - A simple, handmade, operating system with a graphical user interface.
• ChibiOS - a complete development environment for embedded applications including RTOS, an HAL, peripheral drivers, support files and tools

Popular Operating Systems

• Plan 9 from Bell Labs - An OS from the creators of Unix, extending the Unix philosophy of "everything is a file" with a network-centric file system, namespaces and distributed computing.
• Minix - MINIX-Research-Foundation/minix) - Unix-like operating system based on a microkernel architecture
• NetBSD - Unix-like operating system based on the BSD
• OpenBSD - Unix-like operating system based on the BSD
• ReactOS - A free Windows-compatible Operating System
• SystemV - AT&T UNIX System V Source Code