This is the best program for viewing and doing some quick editing of all the MUL files. Can be for anything from viewing the game artwork to adding new animations. This is a very handy program.
Based on Ultima SDK its an Tool to view and alter almost every 2d Client file.
The application once connected to your client files allows a variety of options for visualizing the UO client data.
* Multis - Multi List with Compenent Details for each * Animations - Animation frama data * Items - Item List * Land Tiles - Land Tile List * Texture - Texture List * Gumps - List of Available Gump Components. * Sounds - Sound list * Hue - Hue List * Fonts - Client Fonts * CliLoc - Client Localization Data * Map - Map Data * Light - Light Sources * Speech - Speech Data * Skills - Skill Data * Animdata - Item Animation Data * MultiMap/Facets - Multimap Data (Used for Tmaps) * Dress - Player Body Dress Data * TileData - Item Tile Data * RadarColor - Color Data for Radar Visualization * SkillGrp - Default Skill Groupings.
Download UO Fiddler
It also includes a UOP MUL converter inside the plugins folder