High Quality Content by WIKIPEDIA articles! OmniOutliner is commercial outlining software for Mac OS X produced by The Omni Group. OmniOutliner has most features of a conventional outliner, allowing the user to create nested lists of topics for almost any purpose, but has additional features extending its functionality beyond simple outlining. Recent versions of the software are universal binaries. OmniOutliner received a Special Mention in the 2005 Apple Design Awards, and Macworld gave the "Professional" version its highest rating.