| IOS 11 | Apple Inc. | — | end-user license agreement |
| IOS 12 | Apple Inc. | — | — |
| IOS 13 | Apple Inc. | 2019 | proprietary license |
| IOS 14 | Apple Inc. | 2020 | — |
| IOS 15 | Apple Inc. | — | — |
| IOS 16 | Apple Inc. | 2022 | — |
| IOS 17 | Apple Inc. | 2023 | — |
| IOS 18 | Apple Inc. | 2024 | — |
| IOS 26 | Apple Inc. | 2025 | — |
| IOS 27 | Apple Inc. | — | — |
| IOS 4 | Apple Inc. | 2010 | Apple Public Source License |
| IOS 5 | Apple Inc. | — | Apple Public Source License |
| IOS 6 | Apple Inc. | 2012 | Apple Public Source License |
| IOS 7 | Apple Inc. | 2013 | Apple Public Source License |
| IOS 8 | Apple Inc. | 2014 | Apple Public Source License |
| IOS 9 | Apple Inc. | 2015 | end-user license agreement |
| IPadOS | Apple Inc. | 2019 | proprietary license |
| IPadOS 14 | Apple Inc. | — | — |
| IPadOS 15 | Apple Inc. | — | — |
| IPadOS 16 | Apple Inc. | 2022 | — |
| IPadOS 17 | Apple Inc. | 2023 | — |
| IPadOS 18 | Apple Inc. | — | — |
| IPadOS 26 | — | — | — |
| IPadOS 27 | Apple Inc. | — | — |
| IPCop | — | 2001 | GNU General Public License |
| IPFire | — | — | GNU General Public License |
| IPhone Linux | — | 2008 | — |
| IPhone OS 1 | Apple Inc. | 2007 | proprietary license |
| IPhone OS 2 | Apple Inc. | 2008 | Apple Public Source License |
| IPhone OS 3 | Apple Inc. | 2009 | Apple Public Source License |
| IPodLinux | — | — | GNU General Public License, version 2.0 |
| IRIX | Silicon Graphics | 1988 | — |
| IS-DOS | — | — | — |
| ISIS | Intel | — | — |
| Iskolinux | — | — | — |
| Issabel | — | — | GNU General Public License |
| ISURU Linux | — | — | GNU General Public License |
| ITIX | — | — | GNU General Public License |
| ITsART | — | — | — |
| Jarro Negro | — | — | — |
| Java Card OpenPlatform | IBM | — | — |
| JavaOS | Sun Microsystems | — | proprietary license |
| Jazz Linux | — | — | — |
| Jehanne | — | — | GNU General Public License, version 2.0, GNU Affero General Public License, version 3.0, MIT License |
| JeOS | Canonical Ltd. | — | GNU General Public License |
| JesusFreke ROM | — | — | GNU General Public License, version 2.0 |
| JetOS | Institute for System Programming, State Research Institute of Aviation Systems | — | — |
| Jibbed | — | — | BSD licenses |