OpenBSD (post-CSRG open source type of BSD)

OpenBSD is a Unix like free and open source operating system derived from AT&T UNIX through the Berkeley Software Distribution (BSD) branch, a research Unix derivative developed at the University of California, Berkeley. At the end of 1995, Theo de Raadt branched out from NetBSD. In addition to the operating system as a whole, the project saves a portable version of many subsystems, especially OpenSSH, which is available as a package on other operating systems.

This project is known for its developers' insistence on open source code, good documentation, code correctness, and security. This project has a strict policy on licensing, preferring the ISC license and other variations of the simplified BSD license. Many of the security features are optional or not in other system operations. Developers often audit source code for software bugs and security holes. De Raadt coordinated this project from his home in Calgary, Alberta, Canada. The logo and mascot are puffer fish named Puffy.