XDarwin is a port of the X Window System for the operating systems Mac OS X and Darwin. It allows to run on these operating systems X Window programs.

XDarwin was ported from XonX project, an offshoot of the XFree86 project created by the developers. It is integrated into the upstream source code of the server XFree86 and Xorg and is currently maintained there.

Originally XDarwin needed a running window manager (X window manager ). For a window manager called OroborOSX was written; it was based on the Oroborus window manager, another window manager. This was modified to the extent that he is the original MacOS window managers looked like.

The latest versions of XDarwin can also run " rootless ", ie they integrate into the original MacOS window managers, and therefore do not need a special program such as Oroborus.

Before the introduction of Apple's X11.app XDarwin was the only X server, which was available for OS X. According to the XonX project X11.app itself contains code from XDarwin.