Linux-libre is a GNU package that is maintained from modified versions of the Linux kernel. The aim of the project is to remove any software that does not include its source code, has its source code obfuscated or released under proprietary licenses.
GNU Hurd (usually referred to as the Hurd) is a computer operating system kernel designed as a replacement for Unix, released as free software under the GNU General Public License. It has been under development since 1990 by the GNU Project of the Free Software Foundation.
Redox is a Unix-like microkernel operating system written in the programming language Rust, a language with focus on safety and high performance. Redox aims to be secure, usable, and free. Redox is inspired by prior kernels and operating systems, such as SeL4, MINIX...