| .ttmd |
Trail Tracker Trail Map |
| .typeit4me |
TypeIt4Me Clippings File |
| .tmproject |
TextMate Project |
| .tmtheme |
TextMate Theme File |
| .t2k |
Teach2000 Document |
| .tclogs |
TestComplete Log Configuration File |
| .tsl |
Tracker Status Log |
| .tqs |
Trivia Quiz Shell Program File |
| .timeline |
Timeline Data File |
| .tbx |
ArcGIS for Desktop Toolbox File |
| .usf |
EVGA Precision X Skin File |
| .ui |
User Interface File |
| .u3i |
U3 Application Information File |
| .udcx |
Universal Data Connection File |
| .uml |
UML Data Object Model |
| .unityproj |
Unity 3D Project |
| .ulp |
EAGLE User Language Program |
| .ufo |
Ulead File Object |
| .umlclass |
UML Class Model |
| .uxf |
UML eXchange Format |
| .vcxproj |
Visual C++ Project |
| .vcproj |
Visual C++ Project File |
| .vdx |
Visio Drawing XML File |
| .vbproj |
Visual Studio Visual Basic Project |