Luxor is a free, open-source XML UI Language (XUL) toolkit in released under the GNU General Public License (GPL)
that lets you build UIs using XML and includes an ultra-light weight, multi-threaded web server, a portal engine, a template engine (Velocity),
a scripting interpreter (Python)
and more.

XUL stands for XML UI Language and was pioneered by Mozilla.
XUL is superior to API-based UI toolkits such as Swing or WinForms because it clearly
separates the user interface into four parts:

• content (structure and description of UI elements),


• appearance (look & feel, skin, themes),


• behavior (scripting) and


• locale (localization information for internationalization)

XUL makes UI building easier because it is far simpler than hard-wiring it in Java. XUL also frees
you from the Swing toolkit lock-in because you can create a new rendering engine using a
different UI toolkit such as KDE, Gnome, or WinForms.