There is a lot of open-source os over there so we will present them

OS family Licence State compatibility
Linux Unix GPLv2 Working great
BSD Unix BSD Working have a linux compatiblity layer
GNU Darwin Unix apsl Working
ReactOs windows NT clone gplv2 In developement
Haiku Desktop OS inspired by BeOS MIT In development (pre-alpha) Source/binary compatible with BeOS 5
SkyOS new relases are proprietary
Open Solaris unix CDDL beeing open-sourced,working have a linux compatiblity layer