Mutter is a Wayland display server and X11 window manager and compositor library.

When used as a Wayland display server, it runs on top of KMS and libinput. It implements the compositor side of the Wayland core protocol as well as various protocol extensions. It also has functionality related to running X11 applications using Xwayland. When used on top of Xorg it acts as a X11 window manager and compositing manager. It contains functionality related to, among other things, window management, window compositing, focus tracking, workspace management, keybindings and monitor configuration.

Mutter is used by, for example, GNOME Shell, the GNOME core user interface, and by Gala, elementary OS’s window manager. It can also be run standalone, using the command “mutter”, but just running plain mutter is only intended for debugging purposes.


Mutter is Free Software and is developed in the open.

To contribute, open merge requests at

It can be useful to first look at the GNOME Handbook and the documentation and API references below first.


API Reference