ReactOS
Updated: 02/27/2019 by Computer Hope
ReactOS is a free, open-source operating system that can run Windows programs. It began in 1996 as a project to create a free version of Windows 95. In 2004, the first functional version was released, featuring compatibility for programs compiled for Windows Server 2003.
As of 2020, ReactOS is still in the alpha stage of development, to be used for testing purposes only.