| AmigaOS | Hyperion Entertainment, Haage & Partner, Commodore International | — | end-user license agreement |
| AmigaOS 4 | Hyperion Entertainment | 2006 | proprietary license |
| AOSC OS | Anthon Open Source Community | — | — |
| AROS Research Operating System | — | — | AROS Public License |
| Astra Linux | RusBITech | — | GNU General Public License |
| BeOS | Be Inc., Jean-Louis Gassée, Cyril Meurillon, Jean-Baptiste Maurice Quéru, Benoit Schillings, Dominic Giampaolo, Steve Sakoman | — | 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 |
| Classic Mac OS | Apple Inc. | — | — |
| Copland | Apple Inc. | — | — |
| Darwin | Apple Inc. | 2000 | Apple Public Source License |
| FreeBSD | — | 1993 | 2-clause BSD License |
| FreeRTOS | — | 2003 | MIT License |
| Gentoo Linux | — | — | GNU General Public License |
| JavaOS | Sun Microsystems | — | proprietary license |
| Mac OS 8 | Apple Inc. | — | proprietary license |
| Mac OS 9 | Apple Inc. | — | proprietary license |
| Mac OS X 10.0 | Apple Inc. | 2001 | — |
| Mac OS X 10.1 | Apple Inc. | 2001 | Apple Public Source License |
| Mac OS X 10.2 | Apple Inc. | 2002 | Apple Public Source License, end-user license agreement |
| Mac OS X Leopard | Apple Inc. | 2007 | Apple Public Source License, end-user license agreement |
| Mac OS X Panther | Apple Inc. | 2003 | — |
| Mac OS X Tiger | Apple Inc. | 2005 | — |
| Microsoft Windows | Microsoft | 1985 | proprietary license |
| MkLinux | Free software movement, Open Software Foundation | — | GNU General Public License |
| MorphOS | — | 2000 | — |
| NetBSD | — | 1993 | BSD licenses |
| OpenBSD | OpenBSD Project, Theo de Raadt | — | ISC license |
| OpenSUSE | OpenSUSE Project | — | GNU General Public License |
| OpenWrt | Gábor Juhos, Florian Fainelli, Hauke Mehrtens, Jo-Philipp Wich | 2004 | GNU General Public License, version 2.0 |
| OS/2 | IBM, Microsoft | — | proprietary license |
| Plan 9 | Bell Labs | 1992 | GNU General Public License, version 2.0, MIT License, Lucent Public License |
| RouterOS | MikroTik | — | — |
| RTEMS | Sebastian Huber, Joel Sherrill | — | GNU General Public License |
| Solaris | Sun Microsystems, Oracle Corporation | 1991 | proprietary license |
| Ubuntu GNOME | Canonical Ltd. | 2016 | GNU General Public License |
| Windows 2000 | Microsoft | 2000 | proprietary license |
| Windows Embedded Compact | Microsoft | — | end-user license agreement |
| Windows NT | Microsoft | 1993 | — |
| Windows NT 3.51 | Microsoft | 1995 | proprietary license |
| Windows Server 2000 | Microsoft | 2000 | — |
| Xubuntu | Canonical Ltd., Ubuntu Foundation | 2006 | — |