UTZ file format is used by UIQ software platform. UIQ is based on Symbian operating system and is designed for running mobile devices.

The GUI style in this software platform is defined as theme and the users can change the theme of this software by installing a theme package. The theme package is defined by UTZ file format. This file contains all the information required for defining the complete GUI of the mobile devices including icons, textures, wallpaper and color coding for a number of visual elements. When the user installs this theme package the GUI theme is changed to the settings defined in the new package.