OpenBSD

OpenBSD is a free and open-source Unix-like operating system based on the Berkeley Software Distribution (BSD). Theo de Raadt created OpenBSD in 1995 by forking NetBSD. According to de Raadt, OpenBSD is a research operating system for developing security mitigations. The OpenBSD project maintains portable versions of many subsystems as packages for other operating systems. Because of the project's emphasis on code quality, many components are reused in other software projects. Android uses its C standard library, LLVM uses its regular expression library, and Windows 10 uses OpenSSH with LibreSSL.