| tcvis | TestComplete Test Visualizer Index |
| tcwat | TestComplete Web Accessibility Data |
| tcwcm | TestComplete Web Comparison Data |
| tcws | TestComplete Web Service Project Data |
| tcwtc | TestComplete WebTesting Collection Data |
| tcx | Tacx Exported Training Data |
| tczip | Tekla Structures Exported Data |
| tczl | Tiny Core Linux Xlib |
| tda | Palm To-Do Archive |
| tdata | Tome Editor Data |
| tdb | SlamDB Database |
| tdc | Tableau Data-connection Customization File |
| tddd | Imagine 3D Data Description File |
| tde | Tableau Data Extract |
| tdf | DVD X Copy TDF File |
| tdf | Guide Text Definition File |
| tdh | Borland Turbo Debugger Help Data |
| tdo | Xilinx Text Design Output |
| tdp | Serif DrawPlus Thumbnail |
| tdr | Keysight PLTS TDR Calibration Data |
| tdr | TINA Diagram Results |
| tds | Tableau Data Source |
| tdsx | Tableau Packaged Data Source |
| tdt | PLINK Transmission Disequilibrium Test Report |
| tdt | THOR Datatree File |
| tdt1 | AACS Thumbnail Data File |
| tdt2 | AACS Thumbnail Data File |
| tdump | JIRA Thread Dump |
| tdv | NI Diadem Layout |
| te | Textease Database CT Single-user Database |
| te1 | UltraEdit Template |
| te3 | WinTrack Object File |
| tea | TEA Encrypted Data |
| teacher | SMART Response Teacher Database |
| tec | TECkit Compiled Mapping Table |