FreeDOS is an open-source, MS-DOS-compatible operating system: any program that works on MS-DOS should also run on FreeDOS. It exists to keep classic DOS games, legacy business software and DOS development toolchains usable on modern hardware and virtual machines. Key Features MS-DOS compatibility — runs DOS games and applications, including Wolfenstein 3D, Doom and Commander […]

ReactOS is a free and open-source operating system that reimplements the Windows NT architecture from scratch, with the goal of running Windows applications and drivers without modification. Development has run for three decades, with the latest release being ReactOS 0.4.16. Key Features Windows application and driver compatibility — binary compatibility targets for Windows NT-era software, […]

Haiku is a free and open-source operating system inspired by BeOS, aiming for source and binary compatibility with the BeOS API. It pairs a custom hybrid kernel with a fast, uncluttered native desktop, and remains under active development — Haiku R1/beta6 was released in August 2026. Key Features BeOS API compatibility — running BeOS-era applications […]

SerenityOS is a from-scratch Unix-like operating system started by Andreas Kling. Its userland, C++ standard library, kernel and GUI toolkit are all written in-house, producing a system that deliberately echoes the aesthetics of late-1990s productivity software while offering modern power-user accessibility. Key Features Everything written from scratch — kernel, LibC, libGUI, applications and libraries are […]

Redox OS is a complete Unix-like microkernel operating system written in Rust, focused on security, reliability and safety. It provides source compatibility with POSIX, Linux and BSD programs and is intended as a full alternative to Linux and BSD on both the desktop and in the cloud. Key Features Microkernel architecture in Rust — memory […]

FreeNAS was a free and open-source Network-Attached Storage operating system based on FreeBSD and OpenZFS, developed by iXsystems. In 2020 it was renamed and relaunched as TrueNAS CORE — active development continues under the TrueNAS name. Status Discontinued / superseded. FreeNAS is no longer developed; the final FreeNAS line (11.3) was followed by the rename […]

TrueNAS is a free and open-source Network-Attached Storage (NAS) operating system developed by iXsystems. It turns commodity x86-64 hardware into a powerful storage appliance managed from a web interface. Two editions exist: TrueNAS CORE, based on FreeBSD, and TrueNAS SCALE, based on Debian Linux — both built around the OpenZFS filesystem. Key Features OpenZFS — […]

GhostBSD is a free, open-source, desktop-oriented operating system built on the rock-solid FreeBSD base. It pairs FreeBSD’s stability and security with a simple, elegant desktop experience — a MATE desktop by default and a graphical installer that gets you running without touching the command line. Key Features FreeBSD base — inherits a mature, secure and […]

DragonFly BSD is a free and open-source Unix-like operating system forked from FreeBSD 4.8 in 2003 by Matthew Dillon. It deliberately takes a different technical path from the other BSDs, focusing on scalability across many CPU cores, a hybrid kernel design, and the innovative HAMMER2 copy-on-write filesystem. Key Features HAMMER2 filesystem — a copy-on-write filesystem […]

Category: Operating Systems.