| 386BSD | William Jolitz, Lynne Jolitz | 1992 | BSD licenses |
| BLAG Linux and GNU | — | — | GNU General Public License |
| Gargoyle | — | — | GNU General Public License, version 2.0 |
| Ghost | — | — | GNU General Public License, version 3.0 |
| Haiku | Michael Phipps, Haiku Inc. | 2002 | MIT License |
| HyperWRT | — | — | GNU General Public License |
| KnightOS | — | — | MIT License |
| OpenWrt | Gábor Juhos, Florian Fainelli, Hauke Mehrtens, Jo-Philipp Wich | 2004 | GNU General Public License, version 2.0 |
| PfSense | — | — | Apache License |
| Plan 9 | Bell Labs | 1992 | GNU General Public License, version 2.0, MIT License, Lucent Public License |
| ReactOS | Amine Khaldi, Timo Kreuzer, Eric Kohl, Hermès Bélusca-Maïto, Cameron Gutman | — | GNU Lesser General Public License, GNU General Public License |
| SerenityOS | Andreas Kling | — | 2-clause BSD License |
| SkiftOS | — | — | MIT License |
| Theseus | — | — | MIT License |