| tld | PTC Creo Thermal Temperature Load Data |
| tle | STK Two-line Element Sets |
| tlf | Timing Library Format File |
| tlist | Geomview Transformation Matrices Data |
| tll | LG TV Link-Loader File |
| tlm | Spektrum DX8 Telemetry Log |
| tln | HyperLynx LineSim Schematic |
| tlo | SPSS Table Look File |
| tlog | ArduCopter Telemetry Log |
| tlog | Oracle Database Transaction Log |
| tlr | Tableau Offline License Registration Data |
| tlsv | Topcon TopSURV Database |
| tlt | Trellix Web Design File |
| tlx | CuteSITE Builder Website Data |
| tly | Adobe Photoshop Elements Backup Catalog |
| tm | Catalyst Translation Memory Data |
| tm1 | TimeWise Data |
| tma | DCI TradeManager Catalog Archive |
| tmblr | TumblRipper Data |
| tmbundle | TextMate Bundle |
| tmd | TrueMap Surface Data |
| tmdb | TaskMerlin Database |
| tme | Bryce Time Data |
| tmg | The Master Genealogist Data |
| tml | DB/TextWorks Thesaurus Maintenance Lock |
| tmlanguage | TextMate Language Grammar Data |
| tmm | TimeMap Metadata |
| tmn | Tmin Input File |
| tmpl | Xfire User Interface Template |
| tmplx | Microsoft Windows Starter Group Policy Object XML |
| tmprtf | LexisNexis TimeMap Portable Format Data |
| tmq | TestMaster Questions Data |
| tmr | Free Countdown Timer Backup File |
| tms | Tableau Map Source |
| tmtheme | TextMate Theme |