Yadex is a Doom level editor for POSIX-based systems running The X Window System. It is based upon DEU and is maintained by André Majorel. Yadex can build and edit levels for the alpha and beta versions of Doom, Doom, Doom II, Ultimate Doom, Final Doom and Heretic. There is also limited support for Hexen and Strife. The additional features of several source ports are also supported. Yadex is released under the terms of the GNU General Public License.