| .t | Turing Programming Language Format |
| .t$2a | Timbuktu Pro |
| .t$ab | Timbuktu Pro Address Book |
| .t$m | AVG Internet Security Temporary Format |
| .t00 | TaxCut Federal Data |
| .t01 | TAXWIZ Deluxe Tax Format |
| .t02 | TaxCut 2002 Tax Return Format |
| .t03 | TaxCut 2003 Tax Return Format |
| .t04 | TaxCut 2004 Tax Return Format |
| .t05 | TaxCut 2005 Tax Return Format |
| .t06 | TaxCut 2006 Tax Return Format |
| .t07 | TaxCut 2007 Tax Return Format |
| .t08 | TaxCut 2008 Tax Return Format |
| .t09 | At Home 2009 Tax Return Format |
| .t1 | Male MRI Image Format |
| .t10 | At Home 2010 Tax Return Format |
| .t11 | At Home 2011 Tax Return Format |
| .t12 | H&R Block At Home 2012 Tax Return Format |
| .t13 | H&R Block Tax Software Tax Return |
| .t16 | DAMASK |
| .t2 | TrueType Font Format |
| .t2b | CyBook Thumbnail Image Format |
| .t2d | Technology Transfer Database |
| .t2k | Teach2000 Document Format |
| .t2ks | Teach2000 Exam Results Format |
| .t2kt | Teach2000 Exam Format |
| .t2s | Tier2 |
| .t2t | Txt2tags Text Document |
| .t3 | TADS 3 Game |
| .t3001 | TARGET 3001! Circuit Design Project Format |
| .t32 | Drive Image 5 |
| .t3a | Swift 3D Animation Preset |
| .t3d | Epic Unreal Engine 3D Object Format |
| .t3v | TADS 3 Saved Position |
| .t3x | TYPO3 Compressed Extension |
| .t4 | TerrAlign Alignment Configuration |
| .t44 | DBASE IV Temporary |
| .t49 | HP48/HP49 Specific |
| .t64 | Commodore 64 Emulator Tape Format |
| .t65 | Adobe PageMaker Template |
| .t80 | TANK - API 650/653 Output Document |
| .ta1 | TaxACT 2001 Tax Form |
| .ta9 | TaxACT Tax Document |
| .taac | Sun TAAC Bitmap Image Format |
| .tab | MapInfo Format |
| .tabula-buttons | Tabula Button Library |
| .tabula-doc | Tabula Document |
| .tabula-docstyle | Tabula Document Settings |
| .tac | ActiCalc Data Format |
| .tad | Total Annihilation Demo Saved Game Data |
| .taf | ADRIFT Text Adventure Format |
| .tag | DataFlex Query Tag Name Format |
| .tah | Turbo Assembler Help |
| .tak | TAK Lossless Compressed Audio Format |
| .tal | BrainVoyager QX Talairach Coordinate |
| .tam | Tame Program Settings |
| .tan | Amazon Kindle |
| .tao | Track At Once CD/DVD Image |
| .tap | Commodore 64 Cassette Tape Image |
| .tar | Unix Standard Archive Format, Tape Archive |
| .tar-gz | Gzip Compressed TAR Archive |
| .tar-lzma | TAR Archive |
| .tar-z | TAR Compressed Archive |
| .tar.gz | Compressed Tarball File |
| .tar.gz2 | Misnamed BZ2 Tarball |
| .tar.lzma | LZMA Compressed Tarball |
| .tar.xz | XZ Compressed TAR Archive Format |
| .tar.z | Tar.Z Compressed Archive |
| .taraa | Linux TAR Split Archive |
| .tardist | Tardist Compressed Archive |
| .targa | Truevision TarGA Bitmap Image |
| .targets | MSBuild Targets Format |
| .tas | ADRIFT Text Adventure Save |
| .tat | ESRI Geographic Text Attribute Table |
| .tax | TurboTax Tax Return Format |
| .tax08 | TurboTax 2008 Tax Return Format |
| .tax09 | TurboTax 2009 Tax Return Format |
| .tax10 | TurboTax 2010 Tax Return Format |
| .tax11 | TurboTax 2011 Tax Return Format |
| .tax12 | TurboTax 2012 Tax Return Format |
| .tax13 | TurboTax Tax Return |
| .tax2008 | TurboTax 2008 Tax Return Format |
| .tax2009 | TurboTax 2009 Tax Return Format |
| .tax2010 | TurboTax 2010 Tax Return Format |
| .tax2011 | TurboTax 2011 Tax Return Format |
| .tax2012 | TurboTax 2012 Tax Return Format |
| .tax2013 | TurboTax Tax Return |
| .taxform | QuickBooks Draft |
| .taz | TAR Compressed Archive |
| .tb | Tabbery Tab Format |
| .tb0 | Adobe Photoshop Format Browser Thumbnail Cache Format |
| .tb1 | Borland Turbo C Font |
| .tb2 | Borland Turbo C Font |
| .tb3 | Intel VTune Performance Monitor Sampling Data |
| .tb5 | Intel VTune Performance Monitor Sampling Data |
| .tba | DB/Text Database Primary Textbase Definition |
| .tbb | The Bat! E-mail Hives |
| .tbc | Formula 1 Car Race 2001 Season01 Vehicles |
| .tbd | Document System Document Source Code |
| .tbe | TMPGEnc List |
| .tbf | Trellian Button Factory |
| .tbg | Infinity Engine Game |
| .tbi | FIFA 2001 Data Cmn Be |
| .tbk | ToolBooK Format |
| .tbl | Table Format |
| .tbm | DB/TextWorks Database Menu Screen |
| .tbn | XBMC Folder Thumnail Format |
| .tbp | TASBooks Accounting Data Format |
| .tbr | SoftQuad XMetaL Configuration |
| .tbs | TuneUp Style Boot Screen Format |
| .tbt | Timbuktu Pro Remote Control Software |
| .tbv | Turbo-BrainVoyager Data |
| .tbx | Trados Glossary |
| .tbz | Bzip2 Compressed TAR Archive Format |
| .tbz2 | BZIP/TAR Compressed Archive Format |
| .tc | TrueCrypt Disk Volume Format |
| .tc2 | TurboCAD 2D Drawing Format |
| .tc3 | TurboCAD 2D/3D Mac Drawing Format |
| .tca | The Complete Animator Animation |
| .tcb | Tokyo Cabinet TBZIP |
| .tcc | TimeCalc Classic Proprietary Formatted Data File Format |
| .tcd | Technobox CAD Drawing |
| .tce | TLE File Format |
| .tcf | TTWin 3 Certificate Licensing |
| .tch | Borland C++ Help |
| .tcl | TCL Script Source Code |
| .tclog | TestComplete Log |
| .tcm | TurboCAD Mac Drawing Format |
| .tcp | Tally.ERP Compiled Program Format |
| .tcr | Psion Series 3 EBook Format |
| .tcs | TreeComp Snapshot |
| .tcsh | Unix Shell Script |
| .tct | TurboCAD Template Format |
| .tcw | TurboCAD For Windows Drawing Format |
| .tcx | Garmin Training Center Database XML Format |
| .tcz | PSTextMerge Script Format |
| .tczl | Tiny Core Linux Xlib |
| .td | Borland Turbo Debugger For DOS Configuration Format |
| .td0 | Teledisk Disk Image |
| .td2 | Borland Turbo Debugger For Win32 Configuration |
| .td4 | RollerCoaster Tycoon Track Design Format |
| .td6 | RollerCoaster Tycoon Track Design Format |
| .tda | Palm To Do Format |
| .tda3mt | DivX Author Template Format |
| .tdat | Codewarrior Mac |
| .tdb | EBay Turbo Lister Format |
| .tdc | ALLCapture Project |
| .tddd | 3D Data Description Format |
| .tde | Tableau Data Extract Format |
| .tdf | Total Annihilation Features Format |
| .tdi | Explore (TDI) & Maya Image File (IFF Format) |
| .tdim | Digital F/X Image Format |
| .tdk | Borland Turbo Debugger Keystroke Recording |
| .tdl | Tab Delineated File Format |
| .tdlog | Microsoft Visual Studio |
| .tdm | LabVIEW Binary Measurement Format |
| .tdmb | Trimble Outdoors Navigator Map Bundle |
| .tdms | LabVIEW TDMS |
| .tdms_index | LabVIEW |
| .tdoc | Tabula Document |
| .tdp | Sherif DrawPlus Thumbnail |
| .tdr | Top Draw Vector Graphic |
| .tds | Borland Turbo Debugger Symbol Table Format |
| .tdt | THOR Data Tree Format |
| .tdt2 | Panasonic HD Video Camera Movie |
| .tdv | DIAdem VIEW Module Setup Information |
| .tdx | Visual FoxPro Offline View |
| .tdy | TODAY BuildProfessional Application |
| .tdz | Drobo Firmware Update Format |
| .te | Textease CT Database Format |
| .te3 | Wintrack Object Format |
| .tea | Tea Source |
| .teacher | SMART Response Teacher Database Format |
| .tec | Tecplot ASCII Data Format |
| .ted | Tribes 2 Game Format |
| .tee | TeeChart Office Graphics |
| .tef | TablEdit Tablature Format |
| .tei | TrackEye Image Sequence |
| .tem | Borland C++ Turbo Editor Macro Language Script |
| .temp | Temporary Format |
| .template | Template Format |
| .TemporaryItems | Mac OS X Temporary |
| .ten | TeeChart For .NET Chart Control Template |
| .tep | TopiaryExplorer Project |
| .teq | Saia S-Web-Editor PCD |
| .ter | TerraGen Landscape |
| .term | Apple Mac OS X Terminal |
| .terminal | Apple Mac OS X Terminal Settings Format |
| .terms | Cygwin Demos |
| .terrain | TerraGen Terrain Graphic Data |
| .tes | TECO Macro |
| .testrunconfig | Microsoft Visual Studio Test Run Configuration Format |
| .testsettings | Microsoft Visual Studio Format |
| .tet | Textease Template Format |
| .tew | Wrestling Spirit |
| .tex | TeX/LaTeX Text Document Format |
| .tex0 | Nintendo Wii Texture Format |
| .texi | TEX |
| .texinfo | Texinfo Source |
| .text | Simple Text Format |
| .textclipping | Mac OS X Text Clipping Format |
| .TextExpander | TextExpander |
| .textfactory | BBEdit Text Factory |
| .textile | Eclipse IDE WikiText Document |
| .textmate_init | Unix Shell Script (bash) |
| .texts | Ribbons Texts |
| .texturepack | Arena Wars Texture Pack |
| .textutils | Gnome Desktop |
| .tf | Autodesk Inventor Transcript |
| .tf2 | Team Fortress 2 Data |
| .tfa | Turbo Profiler Area Format |
| .tfc | Unreal Engine 3 Texture Cache Format |
| .tfd | Tape Format Requirements Document Format |
| .tff | IDOLON Tagged |
| .tfh | Turbo Profiler Help |
| .tfil | Blizzard Software Update Format |
| .tfl | Tific Client |
| .tfm | Tagged Font Metric Format |
| .tfmx | Final Musicsystem EXtended Amiga Audio Format |
| .tfp | ProWORX Nxt Full Page Data |
| .tfr | Star Wars Tie Fighter Game Pilot Format |
| .tfrd | Tape Image Format Requirements Document |
| .tfs | Turbo Profiler Statistical Information |
| .tft | Text Formatter Plus Text Information |
| .tfw | World File For TIFF |
| .tfwx | ArcGIS Approximate Affine Transformation |
| .tfx | Tax Exchange |
| .tg | Gzip Compressed TAR Archive |
| .tg4 | TG4 Image Format |
| .tga | Truevision TarGA Bitmap Image |
| .tgb | IPSec VPN Client VPN Configuration |
| .tgc | Terragen Node Clip |
| .tgd | TerraGen World |
| .tgf | Trival Graph Format |
| .tgh | Guitar Hero 3 Tier Settings |
| .tgi | SimCity 4 |
| .tgl | SkyMap Pro Target List |
| .tgmd | ThumbGen Movie Metadata |
| .tgmg | TabGroups Manager For Firefox Exported Group |
| .tgml | Tecumseh Group Markup Language |
| .tgo | Terragen 2 Object |
| .tgp | TGPGuiLib Terragen Plugin |
| .tgq | Dungeon Keeper 2 Movie Game |
| .tgs | GSTree Phylogenetic Tree Information |
| .tgv | Electronic Arts Video |
| .tgw | TerraGen World |
| .tgworld | TerraGen World |
| .tgx | Stronghold |
| .tgz | Gzip Compressed TAR Archive |
| .th | Therion Data Format |
| .tha | Windows Thai Noise-Words List Format |
| .thb | KinuPix Skin |
| .thd | Dolby TrueHD Audio |
| .the | Microsoft Plus! Pack Desktop Theme |
| .theater | IMovie Theater Library |
| .them | Microsoft Windows Desktop Theme |
| .theme | Windows Desktop Theme Format |
| .themepack | Microsoft Windows 7 Theme Pack Format |
| .thewitchersave | The Witcher Save Game |
| .thf | PcAnywhere Thin Host |
| .thl | PowerProducer Background Image Icon |
| .thm | Sony Ericsson Mobile Phone Theme Format |
| .thme | Microsoft Theme Format |
| .thmx | Microsoft Office 2007/2010 Theme Format |
| .thn | Graphics Workshop For Windows Thumbnail |
| .thnl | Graphics Workshop For Windows Thumbnail |
| .thp | TurboTax Text String Format |
| .thr | Thred Embroidery Outline |
| .ths | Corel WordPerfect Thesaurus Dictionary |
| .thumb | JAlbum Thumbnail Format |
| .thumbdata | Google Android Thumbnail Database |
| .thumbdata-idx3 | Android Thumbnail Index |
| .thumbdata3 | Google Android Thumbnail Database |
| .thumbdata3--1763508120 | Android Thumbnail Index |
| .thumbdata3--1967290299 | Android Thumbnail Index |
| .thumbdata3--number | Android MediaProvider Thumbnail Database |
| .thumbdata4 | Google Android Thumbnail Database |
| .thumbdata4--1763508120 | Android Thumbnail Index |
| .thumbdata4--1967290299 | Android Thumbnail Index |
| .thumbdata5 | Google Android Thumbnail Database |
| .thumbdata5--1763508120_0 | Android Thumbnail Index |
| .thumbdata5--1967290299_0 | Android Thumbnail Index |
| .thumbsdb | PixFiler Thumbnail Database |
| .thx | Amiga THX Tracker Music |
| .ti | Timber Compiler |
| .ti0 | Tabula Binary Settings And Initialization |
| .ti1 | Tabula Binary Settings And Initialization |
| .ti2 | Tabula Binary Settings And Initialization |
| .tib | Acronis TrueImage Backup Disk Image Format |
| .tic | TruKnox Cache |
| .tid | TruKnox Transfer Details |
| .tie | CrossTie Installer Format |
| .tif | Aldus Tagged Image File Format (TIFF) Bitmap Image |
| .tiff | Aldus Tagged Image File Format (TIFF) Bitmap Image |
| .tig | Texas Instruments Connect Backup Format |
| .tiger | Crystal Dynamics Game Data Archive Format |
| .tii | Apache Lucene Term Info Index |
| .tikz | Matlab Tikz Script |
| .til | Nova Logic Game Tile |
| .tile | Eclipse Image |
| .tilemap | XML Tilemap Format |
| .TileSkinZip | Elemental Tile Skin |
| .tim | The Incredible Machine Level Format |
| .time | LIGHT Format |
| .tin | Bentley GEOPAK Environmental Modeling Systems |
| .tinf | Microsoft Theme Info |
| .tiny | Gnome Desktop |
| .tinyid | Tiny Village |
| .tip | TuneUp Utilities Icon Package Format |
| .tiprogram | TI-Basic Source Code Format |
| .tir | Tibia RePlay Tibia Movie |
| .tis | TruKnox Captured Device Settings Format |
| .tit | Train Simulator Track Interactive Table |
| .tivo | TiVo Video Format |
| .tiw | Bentley InRoads |
| .tix | DivX Video Download Activation Format |
| .tja | Taikojiro Song Map Format |
| .tjc | Taikojiro Song Map Sequence Format |
| .tjf | IBM Rational ClearCase Transaction |
| .tjp | TaskJuggler Project Format |
| .tk | Tk Language Script |
| .tk1 | Wintec Tools GPS Log |
| .tk2 | Roxio/Take Two Backup |
| .tk3 | TK3 Multimedia EBook Format |
| .tkb | TicketBench Data |
| .tkfl | TKLinks Saver Favorite Links Format |
| .tkl | Takeoff Live PDF Working Data |
| .tkm | TkMOO-light |
| .tkn | Liberty BASIC Application Distribution |
| .tko | Win32/Oficla Malware Format |
| .tkp | MicroImages SML Script Standalone Application |
| .tkr | ESignal Ticker Format |
| .tks | Traktor Pro MIDI Map |
| .tkw | TK Solver |
| .tl | OpenTL Open Track List |
| .tl5 | Timeliner 5 Format |
| .tla | TuneUp Logo Animations |
| .tlb | OLE Type Library |
| .tlbackup | True Launch Bar Backup Settings |
| .tlc | The Logo Creator Format |
| .tld | Tag Library Descriptor Format |
| .tle | TLE File Format |
| .tlg | QuickBooks Transaction Log Format |
| .tlh | Typelib Generated C/C++ Header Format |
| .tli | Typelib Generated C/C++ Inline Format |
| .tlic | Trust Lincense |
| .tlk | BioWare Talk Table Format |
| .tll | LG TV Link-Loader Configuration Format |
| .tlm | Timeline Maker Timeline |
| .tlo | SPSS User Table Lookup Format |
| .tlp | Microsoft TimeLine Project |
| .tlq | Art Explosion T-Shirt Factory Deluxe |
| .tlr | Tableau Offline License Registration |
| .tls | TuneUp Utilities Logon Screen Format |
| .tlt | Trellix Web Design |
| .tlv | TruLASER View Geometry Data |
| .tlx | Wintertree Dictionary Format |
| .tly | Adobe Photoshop Elements Backup Catalog |
| .tlz | Unix TLZ Compression Engine Format |
| .tlzma | LZMA Compressed Tar Archive |
| .tm | TeXmacs Document |
| .tm1 | TimeWise |
| .tm2 | Playstation 2 TIM2 Bitmap Format |
| .tm8 | TMC Audio Format |
| .tmb | Timbuktu Pro Connection Document Format |
| .tmbundle | TextMate Bundle Format |
| .tmc | Unknown File Extension |
| .tmd | TextMaker Document Format |
| .tmdb | TaskMerlin Database |
| .tme | Bryce Animation Time Curve Format |
| .tmf | Corel WordPerfect Tagged Font Metric |
| .tmh | Trace Message Header |
| .tmi | Thin Client Media-3 Encoded Video |
| .tmk | Turbo Pascal Tour |
| .tml | PADGen |
| .tmlanguage | TextMate Grammar Format |
| .tmm | TimeMap Metadata |
| .tmo | 3D Custom Girl Animation Format |
| .tmp | Temporary Format |
| .tmpl | SWISH-E Example Format |
| .tmpreferences | TextMate Preference |
| .tmproj | TextMate Project Format |
| .tmproject | TextMate Project |
| .tmprtf | TimeMap Portable |
| .tmq | TestMaster |
| .tmr | Apimac Timer Settings Format |
| .tms | Timeless Time & Expense Multi-user Settings Format |
| .tmtheme | TextMate Theme Format |
| .tmv | TextMaker Document Template Format |
| .tmvt | TimeMap Template |
| .tmw | Timeless Time & Expense Multi-user Security Format |
| .tmx | Translation Memory EXchange Format |
| .tmz | Medigraph Compressed Database |
| .tmzip | Theme Manager Zip Format |
| .tn | LG Encoded JPG Image Format |
| .tn1 | Tiny Bitmap Image Format |
| .tn2 | Tiny Bitmap Image Format |
| .tn3 | Tiny Bitmap Image Format |
| .tn? | TiNY 2D Graphic |
| .tna | Topocad Net Adjustment |
| .tne | Manga Studio Tone Format |
| .tnef | Transport Neutral Encapsulation Format |
| .tnf | Transport Neutral Encapsulation Format |
| .tng | Namo WebCanvas Vector Graphic |
| .tnl | Thumbnail Image Format |
| .tnr | GPS Pathfinder ProXR/XRS Firmware |
| .tns | TI-Nspire Document |
| .tnsp | Texas Instruments TI-Nspire PublishView Document Format |
| .tnt | TurnTool 3D Model |
| .tnx | PCL Toolkit Text Extraction |
| .tny | TiNY Bitmap Image |
| .toast | Roxio Toast Disk Image Format |
| .tob | ZEMAX Object Data |
| .toc | Table Of Contents Format |
| .tocf | Eudora For Mac TOC |
| .tod | JVC Everio Video Capture Format |
| .toe | Touch Environment Project |
| .tof | Mr. Photo Temporary Thumbnail |
| .tofp | Toshiba Fingerprint Utility Settings Backup |
| .toh | Infinity Engine Game |
| .tok | Borland C++ 4.x External Tokens |
| .tokend | Smart Card Support Mac |
| .tol | AOL Tool Format |
| .tom | MediGraph Database |
| .tombRaider 3 | Tomb Raider 3 Save Game |
| .ton | FMS32 Protocol |
| .tool | Apple Mac OS X Terminal |
| .tools | DJGPP Tools |
| .top | Evernote Handwritten Notes And Sketches Format |
| .topc | TopicCrunch Stored Search Project |
| .topprj | TopSolid Project Format |
| .topx | E-sword Topic Note |
| .tor | Star Wars: The Old Republic Asset Format |
| .torchdownload | Torch Web Browser Partial Download |
| .torrent | BitTorrent Information Format |
| .tos | Atari ST TOS Archive |
| .tot | Bioware Infinity Game Engine Talk Table Override Text |
| .totalsbackup | Kedisoft Totals Database Backup Format |
| .totalsdb | Kedisoft Totals Database Format |
| .totalslayout | Totals Invoice Layout Format |
| .totalssyncdb | Kedisoft Totals Sync Database Format |
| .tox | Touch Component |
| .toy | Catz & Dogz Game |
| .tp | Beyond TV Transport Stream Format |
| .tp0 | Mascom PVR Video Format |
| .tp3 | Harvard Graphics DOS 3.0 Template Format |
| .tp4 | RollerCoaster Tycoon Track Design Screenshot Format |
| .tp7 | MODTRAN |
| .tpa | CorelDRAW Custom Graphic |
| .tpark | ThemePark Project Format |
| .tpb | GROMACS Portable Binary Run Input Format |
| .tpc | Topic Connection Placeholder |
| .tpd | JVC Cyberlink TOD Video Format |
| .tpe | Clarion Example |
| .tpf | Transit NXT Pack Translation Format |
| .tpg | TREAT Project |
| .tph | Turbo Pascal Help |
| .tpi | EDIUS Plugin Format |
| .tpic | TrueVision TARGA Image |
| .tpj | Nova Logic Game Terrain Project |
| .tpk | Tizen Application Package |
| .tpkey | TexturePacker License |
| .tpl | Generally A Template Format |
| .tpm | TextPad Macro Format |
| .tpo | TOPO! MapXchange Document |
| .tpp | Borland Pascal Protected Mode Units |
| .tpq | TOPO!Pro Map |
| .tpr | TMPEG Enc Video Conversion Project Format |
| .tps | Scam Torrent Format |
| .tpsdb | Print Shop Project |
| .tpt | ThumbsPlus Thumbnail Template |
| .tpu | Turbo Pascal Unit Format |
| .tpw | Borland Turbo Pascal Unit |
| .tpx | Photo Express Template Format |
| .tpz | Amazon Kindle Topaz E-book Format |
| .tqd | Torq Song Information |
| .tqf | Rational Test RealTime |
| .tql | Microsoft SQL Server Query Analyser Header |
| .tr | TomeRaider EBook Format |
| .tr0 | SPICE Transient Analysis Output |
| .tr1 | IBM Voice Type Languages Addword |
| .tr2 | Borland Turbo Debugger Session-state Settings |
| .tr3 | TomeRaider EBook Format |
| .tr4 | SPICE Transient Analysis Output |
| .tr5 | OnyxTree Professional Format |
| .tr6 | SPICE Transient Analysis Output |
| .tr7 | SPICE Transient Analysis Output |
| .tr8 | SPICE Transient Analysis Output |
| .tr9 | SPICE Transient Analysis Output |
| .tra | WinTrack Railroad Track Format |
| .trace | VMware ThinApp Trace Log Format |
| .tracwiki | Eclipse IDE WikiText |
| .trak | Native Instruments Traktor Content Pack Format |
| .transcriptstyle | Apple IChat Transcript Style |
| .trashes | Google Android Mobile Phone |
| .trashinfo | Trash Storage Metadata |
| .tray | Corel CONNECT Tray Format |
| .trb | Animation Master Turbulence Extension |
| .trc | Oracle SQL*Net Trace Debug Format |
| .trce | Corel Trace |
| .trd | TrID Definitions Package Format |
| .tre | EA SPORTS Game |
| .trec | Camtasia Studio Recorded Session |
| .tree | ES-Builder Tree |
| .trf | LFToolkit Transformation Rules |
| .trg | Symantec LiveUpdate |
| .tri | FaceGen Polygonal Model Format |
| .TriDefMovie | TriDef Movie |
| .TriDefPhoto | TriDef 3D Photo Transformer Depth Map |
| .trif | TRIF Tiled Raster Interchange Format Bitmap Format |
| .trk | Garmin GPS PCX5 Track Format |
| .trl | Topocad |
| .trm | Terminal Settings Format |
| .trn | Microsoft SQL Server Transaction Backup Format |
| .tro | IBM Voice Type Languages Vocable |
| .trp | MPEG-2 HD Video Format |
| .trr | GROMACS Full-precision Trajectory |
| .trs | Rosetta Stone Language Data Format |
| .trt | Team Sports Scheduling System Report Template |
| .tru | True Basic Source |
| .truck | Rigs Of Rods Truck Definition Format |
| .trv | Traverse PC Desktop Survey Data |
| .trx | Microsoft Visual Studio Test Results Format |
| .trx_dll | Windows Startup Format |
| .trz | Norton Antivirus Rapidrelease Definition Update |
| .ts | MPEG-TV Recorded Format |
| .ts0 | Tio32 Script |
| .ts1 | VirtualBus Texture Description Format |
| .ts2 | Time Stamp Project Information |
| .ts4 | Recorded Multimedia |
| .tsb | 3dMD Or 3Q Viewer 3D Image |
| .tsc | Microsoft Windows WinHelp Related Format |
| .tsd | NovaLogic Game Tile Surface Define |
| .tsf | ProWORX Nxt Symbol Format |
| .tsg | TSG Data |
| .tsi | Traktor Pro MIDI Map Format |
| .tsk | Pocket PC Skin |
| .tsm | Turbo Assembler For OS/2 Manual Format Format |
| .tsn | RatLab Toolkit |
| .tso | Tactical Situation Object XML |
| .tsp | Microsoft Windows Telephony Service Provider Format |
| .tsr | TSR Launcher |
| .tss | Team Sports Scheduling System Project Format |
| .tst | TestPoint Test Format |
| .tstream | SwarmPlayer Video Stream Control Format |
| .tsv | Tab Separated Values Format |
| .tsw | NI TestStand Workspace |
| .tsx | Team Sports Scheduling System XML Project |
| .tsz | Trillian Skin Format |
| .tt | Microsoft Visual Studio Text Template Format |
| .tt10 | Intuit Turbotax Tax 2010 Return Format |
| .tt11 | TurboTax Canada 2011 Tax Return Format |
| .tt12 | TurboTax 2012 Tax Return Format |
| .tt13 | TurboTax 2013 Tax Return |
| .tt2012state | TurboTax 2012 State Tax Form |
| .tt4 | TempTale |
| .tta | TTA Lossless Audio Codec Format |
| .ttarch | Telltale Games Game Data Format |
| .ttarch2 | The Walking Dead Season Two Game Data |
| .ttbk | Canadian TurboTax 2010 Backup Format |
| .ttbl | TTPLayer Play List |
| .ttbs | Microsoft PowerPoint For Mac Toolbar |
| .ttc | TrueType Font Collection |
| .ttd | Tinytag Data Log |
| .tte | Private Character Editor Format |
| .ttf | TrueType Font Format |
| .ttg | Command & Conquer Red Alert 3 |
| .tth | Vampire - Bloodlines Game |
| .tti | Beast Trojan |
| .ttk | Alchemy Catalyst Translation Toolkit Format |
| .ttkgp | TatukGIS Editor Project Format |
| .ttm | Tower Toppler Level Format |
| .ttn | Bentley InRoads Topologically Triangulated Network |
| .ttpl | TTPLayer Play List |
| .tts | ToolBook Translation System Format |
| .ttt | TestTrack Pro Database |
| .ttx | TRADOS TagEditor TRADOStag XML Format |
| .ttxt | MPEG-4 Timed Text Subtitles Format |
| .tty | Macromedia Dreamweaver |
| .ttz | Vampire The Masquerade |
| .tu | Turing Source Code Format |
| .tu? | Standard Mail Archive |
| .tub | Corel PaintShop Photo Pro Picture Tube Format |
| .tud | ThumbsPlus Graphics |
| .tui | NI LabWindows User Interface |
| .tun | Lego Racers Music Format |
| .tuneao | Marathon 2 Aleph One |
| .tur | Turing Program Source Code Format |
| .turboc3 | Borland Turbo C Makefile |
| .tut | Children Of The Nile Tutorial Format |
| .tuw | Microsoft Office |
| .tv | Corel Paradox Table View Settings |
| .tv1 | Corel WordPerfect Overflow |
| .tv2 | Corel WordPerfect Overflow |
| .tv3 | Corel WordPerfect Overflow |
| .tv4 | Corel WordPerfect Overflow |
| .tv5 | Corel WordPerfect Overflow |
| .tv6 | Corel WordPerfect Overflow |
| .tv7 | Corel WordPerfect Overflow |
| .tv8 | Corel WordPerfect Overflow |
| .tv9 | Corel WordPerfect Overflow |
| .tva | Truevision3D Animated Actor |
| .tvc | IBM Lotus 1-2-3 Table |
| .tvd | Apache Lucene Term Vector Documents |
| .tvex | Apple QuickTime MoviePlayer Extension |
| .tvf | DBASE Table View Settings |
| .tvg | Toon Boom Vector Graphics |
| .tvixie | TViXiE Effects |
| .tvj | TrueView Job Ticket |
| .tvl | TurboTax Format |
| .tvm | The Tube |
| .tvn | Yamaha Tyros 2 Voice |
| .tvod | Apple QuickTime Movie Or JPEG Picture |
| .tvp | TVP Animation Animation Data |
| .tvpi | TitanTV Television Listing Format |
| .tvr | Navicat For MySQL |
| .tvs | TeamViewer Session Format |
| .tvt | IBM Lenovo ThinkVantage Rescue And Recovery |
| .tvvi | TitanTV Television Listing Format |
| .tvx | Apache Lucene Term Vector Index |
| .twain | Adobe Acrobat TWAIN 1.8 Specification |
| .twb | Tableau Workbook Format |
| .twbx | Tableau Packaged Workbook Format |
| .twc | TTWin Configuration Format |
| .twd | MindMapper Brainstorm And Visual Map |
| .twdx | MindMapper Document |
| .twe | ThinkWave Educator Data |
| .twf | ArcView World Coordinates |
| .twg | CARE-S InfoWorks Trade Waste |
| .twi | SDDS Toolkit |
| .twig | Twig Source |
| .twiki | Eclipse IDE WikiText |
| .twk | TweakS |
| .twl | Naviguide Binary Route |
| .twm | TeamWORKS Module Launcher Format |
| .twp | Teamwork Planner Project |
| .tws | TextPad Workspace |
| .twt | Carmageddon 2 Carpocalyse Now Saved Game Format |
| .twv | VCM-ROM Linker Voice |
| .tww | Tagwrite Template |
| .twz | TheWord Compressed Module Format |
| .twzip | TheWord Compressed Module Format |
| .tx | Photoline 5 Help |
| .tx0 | Portable Radiation Package Data |
| .tx3g | MPEG-4 |
| .tx8 | 8-bit DOS ASCII Text |
| .tx? | LoseThos Text |
| .txa | Clarion Exported To Text Format Format |
| .txb | Descent / Descent 2 Encoded Briefing |
| .txc | Urban Chaos Game |
| .txd | Grand Theft Auto III Texture Dictionary |
| .txe | Enriched Text |
| .txf | Tax Exchange Format |
| .txh | Light Markup Language Text |
| .txi | KOTOR2 Game |
| .txl | Genesis3D Texture |
| .txm | CFPwinMan Document |
| .txn | MySpace IM Log Format |
| .txo | Panda3D Texture Object |
| .txp | Tweaking Toolbox XP Import/export Setting |
| .txr | CorelDraw Custom |
| .txt | Simple Text Format |
| .txt12 | IRI Scouting Database XML |
| .txtdt | TitleWriter DVD Text Data |
| .txtenx | Egis Encrypted TXT |
| .txtr | The Sims Texture |
| .txtrpt | CommScope Teletilt Control System Report |
| .txtz | EBook |
| .txu | CncCUT Program Text |
| .txv | RapidReader TextVision |
| .txw | Yamaha TX-16W Wave Format |
| .txx | Insight Segmentation And Registration Toolkit |
| .txz | XZ Compressed TAR Archive Format |
| .tx_ | Compressed Txt Format |
| .tyimport | Typinator Imported Set Format |
| .tym | Adobe PageMaker Time Stamp |
| .typeit4me | TypeIt4Me Clippings Format |
| .tyset | Typinator Set Format |
| .tz | TAR.Z Compressed File Archive |
| .tzb | TAR.Z.btoa Compressed File Archive (TAR - Compress - Btoa) |
| .tzd | Netscape Communicator |
| .tzi | Microsoft Windows CE Time Zone Information |
| .tzp | TrueZIP Ecnrypted JAR Java |
| .tzx | ZX Spectrum Tape Image Poke Format |
