| Armed Forces mobile system | — | — | proprietary license |
| ChorusOS | Chorus Systèmes, Oracle Corporation, Sun Microsystems, Institut National de Recherche en Informatique et en Automatique | — | BSD licenses, GNU Lesser General Public License, Mozilla Public License, Sun Public License |
| FreeBSD | — | 1993 | 2-clause BSD License |
| Gentoo Linux | — | — | GNU General Public License |
| Illumos | — | — | Common Development and Distribution License version 1.0 |
| JavaOS | Sun Microsystems | — | proprietary license |
| MirOS BSD | — | — | BSD licenses |
| NetBSD | — | 1993 | BSD licenses |
| NeXTSTEP | NeXT | — | proprietary license |
| OpenSolaris | Sun Microsystems | — | Common Development and Distribution License version 1.0 |
| OpenWrt | Gábor Juhos, Florian Fainelli, Hauke Mehrtens, Jo-Philipp Wich | 2004 | GNU General Public License, version 2.0 |
| Plan 9 | Bell Labs | 1992 | GNU General Public License, version 2.0, MIT License, Lucent Public License |
| Red Hat Linux | Red Hat | 1994 | GNU General Public License |
| RTEMS | Sebastian Huber, Joel Sherrill | — | GNU General Public License |
| Solaris | Sun Microsystems, Oracle Corporation | 1991 | proprietary license |
| SunOS | Sun Microsystems | — | proprietary license |
| Zephyr | Wind River Systems, Linux Foundation | — | Apache Software License 2.0 |