| AmayaOS | — | 2014 | GNU General Public License, version 3.0 |
| Android Canary | — | 2025 | — |
| Android Go | — | 2017 | — |
| ARX | Acorn Computers | — | — |
| BeOS | Be Inc., Jean-Louis Gassée, Cyril Meurillon, Jean-Baptiste Maurice Quéru, Benoit Schillings, Dominic Giampaolo, Steve Sakoman | — | proprietary license |
| BridgeOS | Apple Inc. | — | proprietary license |
| BSD | — | — | — |
| Contiki | Adam Dunkels | — | 3-clause BSD License |
| Darwin | Apple Inc. | 2000 | Apple Public Source License |
| DEMOS | National Research Centre Kurchatov Institute | — | BSD licenses |
| Escape | — | — | GNU General Public License, version 2.0 |
| FreeNOS | — | — | GNU General Public License, version 3.0 |
| GeckoLinux | — | 2016 | — |
| Haiku | Michael Phipps, Haiku Inc. | 2002 | MIT License |
| HI-UX | Hitachi | 1987 | — |
| HP Multi-Programming Executive | Hewlett-Packard | — | — |
| HP-UX | Hewlett Packard Enterprise | 1984 | proprietary license |
| IBM AIX | IBM | 1986 | proprietary license |
| Integrity | Green Hills Software | — | — |
| IOS | Apple Inc. | 2007 | proprietary license |
| IRIX | Silicon Graphics | 1988 | — |
| JetOS | Institute for System Programming, State Research Institute of Aviation Systems | — | — |
| Kaspersky OS | Kaspersky Lab | — | — |
| KnightOS | — | — | MIT License |
| LynxOS | Lynx Software Technologies | — | — |
| 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 Panther | Apple Inc. | 2003 | — |
| Mac OS X Public Beta | Apple Inc. | — | — |
| Mac OS X Tiger | Apple Inc. | 2005 | — |
| MINIX | Andrew S. Tanenbaum | — | 3-clause BSD License |
| MINIX 3 | Andrew S. Tanenbaum | — | BSD licenses |
| MOS | — | — | — |
| NeXT Computer | — | 1988 | — |
| NeXTSTEP | NeXT | — | proprietary license |
| Nucleus RTOS | Mentor Graphics | — | — |
| Nut/OS | Ethernut | 2000 | BSD licenses |
| NuttX | Apache Software Foundation | — | Apache License, Apache Software License 2.0 |
| Olivetti X/OS | Olivetti | — | — |
| OpenDarwin | — | 2002 | — |
| OpenSolaris | Sun Microsystems | — | Common Development and Distribution License version 1.0 |
| OPENSTEP | — | — | — |
| OSF/1 | Open Software Foundation | — | — |
| PC/IX | Interactive Systems Corporation | — | — |
| PikeOS | SYSGO | — | — |
| Plurix | Federal University of Rio de Janeiro | — | — |
| PureDarwin | — | — | — |