Imagine running your favorite Windows applications and drivers in an open-source environment you can trust. That's ReactOS. A free, open source, Windows compatible operating system. It's written from scratch, not based on Linux, with 27,000,000+ lines of code and growing. More than 100 developers contributed along the years It aims to be lightweight with only 500MB HDD and 96MB RAM as the current minimum requirement. Developers enjoy a fast, CMake based build system that supports GCC, Clang and MSVC toolchains (including Visual Studio solutions support).