| .l | Lex Language Source Format |
| .l01 | ARC Digitized Raster Graphics Format |
| .l2l | IBM Voice Type Languages Addword |
| .l2p | BM Voice Type Languages Addword |
| .l2r | Lineage II Replay |
| .l32 | Swift Line 21 Caption |
| .l3d | Black & White Graphics Format |
| .l4d | Cinema 4D Layout Settings Format |
| .l5k | RSLogix 5000 |
| .l6t | Line 6 GearBox Tone Format |
| .la | La Lossless Compressed Audio Format |
| .la0 | LucasArts Game Data |
| .la1 | LucasArts Game Data |
| .la2 | LucasArts Game Data |
| .laa | LucasArts AdLib Audio |
| .lab | Corel WordPerfect Label Definition Format |
| .labx | CASSY Lab |
| .laby | Laby Level Format |
| .laccdb | Microsoft Access 2007/2010 Database Lock Format |
| .lad | Daylon Leveller Animation Data |
| .lae | Local Authentication Export |
| .laf | Lingoes Appendix |
| .lai | GNU Libtool Temporary |
| .lak | Kashmir |
| .lam | Netscape Media Player Streaming Audio Metafile |
| .lamp | ArchiCAD For MAC Geometric Description Language |
| .lan | Erdas LAN Image Format |
| .lanalyser | Novell Netware LANalyzer Trace |
| .land | Userland Frontier |
| .lang | Skype Language Settings Format |
| .lao | EPSON SMART PANEL |
| .lar | Liquid Audio Player Registration |
| .las | LIDAR Data Exchange Format |
| .lasso | Lasso Database Driven Web Page |
| .lastbuildstate | MSBuild Exported Build |
| .lastlogin | Minecraft User Settings Format |
| .lat | LaTeX |
| .latex | Latex Text Document Format |
| .launch | Zend Studio Debugger Configuration |
| .launcherex_sourcerecord | Foston Google Android |
| .lav | Liquid Audio Player Voucher |
| .lavs | Liquid Audio Secured Download |
| .lax | AnetHelpTool JavaHelp Viewer |
| .lay | Apple DVD Studio Pro Layout Format |
| .layerdiagram | Microsoft Visual Studio Layer Diagram |
| .layout | Apple MainStage Layout Format |
| .layoutdesigner | QuickBooks Layout Designer Template |
| .lb | LBwin Project |
| .lba | Liberty BASIC |
| .lbc | Cloaked Affiliate Link Builder Saved Link Format |
| .lbd | Life Balance User Data |
| .lbe | Life Balance Xml-based Data Exchange |
| .lbf | Bioshock 2 Configuration |
| .lbg | DBASE IV Label Generator Data |
| .lbi | Adobe Dreamweaver Library Format |
| .lbk | VersaPro Local Logic Block Backup |
| .lbl | Database Label Format Format |
| .lbm | Interleaved Bitmap Format |
| .lbo | DBASE IV Compiled Label |
| .lbp | ProWORX Nxt Logic Pointer |
| .lbr | EAGLE Library Format |
| .lbs | Omnis Studio Application Format |
| .lbt | Visual FoxPro Additional Label Description Format |
| .lbu | Cloaked Affiliate Link Builder Settings Format |
| .lbx | Visual FoxPro Main (DBF) Label Description Format |
| .lbxcol | Libronix DLS Resource Collection |
| .LBXDTP | Libronix DLS Data Type |
| .lbxlls | Logos Libronix 3.0 |
| .lbxoeb | Libronix DLS Resource |
| .lcb | Concept2 LogCard Utility LogCard Backup Image |
| .lcc | Capture One PRO Format |
| .lcd | Abbyy Finereader Sprint Format |
| .lcf | ArchiCAD Library Container Format |
| .lch | IBM Works For OS/2 Chart |
| .lci | IBM Voice Type Languages Newuser |
| .lck | Lock Format |
| .lcl | Localization |
| .lclw | ClarisWorks Art Library |
| .lcm | Lipikar Custom Map Format |
| .lcn | Corel WordPerfect Dictionary Format |
| .lcp | FARSITE Landscape Data |
| .lcs | ACT! History |
| .lct | Electrical Filter Design |
| .lcx | LC Model |
| .ld | Telix Long Distance Codes |
| .ld1 | DBASE Overlay |
| .ld2 | Lingoes Compiled Dictionary Format |
| .ld4 | ACCPAC Plus Menu |
| .lda | LaserData Image Format |
| .ldb | Microsoft Access Record-Locking Information Format |
| .ldd | LEGO Digital Designer |
| .ldf | Microsoft SQL Server Log Format |
| .ldi | LDIF Address Book Interchange Format |
| .ldif | LDIF Address Book Interchange Format |
| .ldl | Corel Paradox Delivered Library |
| .ldm | VolumeViz Multi-resolution Volume Format |
| .ldmt | Likno Drop-Down Menu Trees |
| .ldo | Nova Logic Game Loadout Text |
| .ldp | Label Designer Plus DELUXE Data |
| .ldr | LDraw Model Format |
| .lds | Linux Compile Time Header Format |
| .ldt | ZENAX Source EULUMDAT Format |
| .ldw | Virtual Villagers Save Game Format |
| .ldx | Liquid Studio Liquid Executable Bytecode |
| .ldz | Microsoft Visual Studio DSM Project |
| .le | Le Mac OS X |
| .led | Sony AIBO AIBO LED File Format |
| .lef | LEN Exchange Format |
| .leg | LEGOCAD |
| .legal | DaveTech Legal Document |
| .lei | Leica SP1 Image Session |
| .lemon | LemonShare.net Download Format |
| .lens | Autodesk Stitcher Camera Profile |
| .lep | Label And Envelope Designer Plus 2000 |
| .less | LESS Style Sheet Format |
| .let | Nuke Randomic Life Generator |
| .letter | Undeliverable Mail Format |
| .lev | Worms Map |
| .lex | Adobe Linguistic Library Data Format |
| .lf | SoftwareKey License |
| .lfa | Life Forms |
| .lfe | LFClient Document |
| .lff | LucasFilm Format Image Format |
| .lfm | LifeForm Format |
| .lfo | Camel Audio Alchemy Preset Format |
| .lfp | IPRO View Database Format |
| .lfs | Samsung Test Picture Image Format |
| .lft | ChiWriter Laser Printer Font |
| .lg0 | IBM Tivoli Monitoring Log |
| .lg1 | IBM Tivoli Monitoring Log Backup |
| .lg2 | HotMux Thermocouple Data Log |
| .lga | Microsoft Windows Application Log |
| .lgb | QuickBooks Little Green Box |
| .lgc | SimpleK Database Format |
| .lgd | Windows Application Log |
| .lgf | Microsoft Windows Application Log |
| .lgg | Microsoft Windows Application Log |
| .lgh | HMI Historical Log Format |
| .lgi | Multimedia Logic Format |
| .lgj | Microsoft Windows Application Log |
| .lgk | Microsoft Windows Application Log |
| .lgl | LeechGet Download Queue Format |
| .lgm | Microsoft Windows Application Log |
| .lgn | Microsoft Windows Application Log |
| .lgo | Logo Instructions Format |
| .lgp | Final Fantasy Game Archive Format |
| .lgq | Microsoft Windows Application Log |
| .lgr | Microsoft Windows Application Log |
| .lgs | Microsoft Windows Application Log |
| .lgt | Urban Chaos Game |
| .lgv | Debugging Tools For Windows Logger Log |
| .lgw | ANSYS |
| .lgz | Windows Application Log |
| .lha | LH ARC Compressed Archive |
| .lharc | LH ARC Compressed Archive |
| .lhr | Quicken Financial Life For Mac Financial Data Format |
| .lhs | Literate Haskell Programming Language Source Code Format |
| .lhw | LHWarp Compressed Amiga Archive |
| .lhx | LineTracker Firmware Upgrade |
| .lhz | LHA Compressed File Archive |
| .li3d | BeLight Live Interior 3D Design Format |
| .lia | P-CAD Schematics Library |
| .lib | Microsoft Linker Input Library Format |
| .lib4d | Cinema 4D Library |
| .library | CATIA Library |
| .library-ms | Microsoft Windows 7 Library Description Format |
| .lic | Unix Software License Format |
| .licensekey | Coriolis IPartition License Information Format |
| .licenses | Microsoft Visual Studio Licensed Classes Format |
| .lickey | AVS4YOU License Key |
| .licrypt | Encrypted |
| .licx | Microsoft Visual Studio License Format |
| .lid | Quicken 2002 Deluxe Format |
| .lif | Compressed Format Archive (CA-Clipper Installer) |
| .life | LIGHT Format |
| .lig | INet-Server |
| .lightwave | Lightwave 3D Layered Object |
| .lik | Trojan.Win32.Agent.lik |
| .lily | PCSX2 LilyPad Configuration Format |
| .lin | AutoCAD Linetype Definition |
| .link | Apple IPod Link Format |
| .linux | Linux |
| .linx | Bridge Base Format |
| .lip | SLIP Format Format |
| .liquid | Shopify Liquid Template |
| .lir | ADI Ocelot Settings |
| .lis | Structured Query Reporting Output Format |
| .lisp | LISP Translators Format |
| .list | JAR Index Format |
| .lit | Microsoft Reader EBook Format |
| .litemod | Minecraft Mod |
| .little | Mozilla Firefox Start-up Cache |
| .liv | Living Actor Actor |
| .livereg | Symantec Livereg Antivirus Session Format |
| .livesubscribe | Symantec Antivirus Update Catalog |
| .liveupdate | Symantec Liveupdate Format |
| .lix | ExtendSim Library Format |
| .lizd | BeLight Live Interior 3D Compressed Design Format |
| .ljp | Lossless JPEG Bitmap Image Format |
| .lk# | Autodesk Multi-user Coordination Lock |
| .lkg | HP-UX Configuration |
| .lkh | Worm.Generic.LKH Virus |
| .lko | Microsoft Outlook Express |
| .lkr | MPLAB Linker |
| .ll | List & Label Preview Format |
| .llb | LabVIEW Application Program Library Format |
| .llc | LapLink Saved Connection |
| .llm | Linden Lab Mesh Format |
| .llp | VersaPro Local Logic Block |
| .lls | Windows System |
| .llt | Liquidity Lighthouse Transaction Format |
| .llv | Lizard Safeguard License |
| .llx | LabVIEW Library Backup Format |
| .lm4 | Steinberg VST Sample |
| .lma | Learning Mobile Author (LMA) Project |
| .lmbs | Adobe Photoshop For Mac Filter |
| .lmd | Abbyy Finereader Sprint |
| .lmf | Library Mapping And Altera Data Interchange |
| .lmg | CryENGINE Locomotion Group Animation |
| .lmh | Memory Hacking Software Memory |
| .lmk | Sothink Logo Maker Logo Format |
| .lmlpack | Kashmir 3D Link |
| .lmp | Doom Recorded Demo |
| .lmr | QuickBooks Loan Manager Data |
| .lms | Light-O-Rama Musical Sequence Format |
| .lmt | RPG Maker 2000/2003 Map Tree |
| .lmu | RPG Maker Map Format |
| .lmv | Adobe Flash Source Code |
| .lmx | Nokia Landmark Exchange Format |
| .ln | UNIX Lint |
| .lna | Xilinx ISE |
| .lnc | Football Manager Player |
| .lnd | 3D Landscape Data |
| .lnf | Oyoaha Lookandfeel Interface Elements |
| .lng | Language Definition Format |
| .lngx | KeePaas Language |
| .lnk | Windows Shortcut Format |
| .lnm | Corel WordPerfect SGML Alias |
| .lnp | µVision Linker Input Format |
| .lns | AVG Anti-Virus Language |
| .lnst | Adobe InDesign Format |
| .lnt | PC-lint Configuration Format |
| .lnx | Atari Lynx ROM Image Format |
| .lnz | Petz Linez |
| .lo | Interleaf Compiled Lisp Format |
| .loaderbackup | BlackBerry Backup |
| .loaders | GTK+ Loaders Format |
| .loadtest | Microsoft Visual Studio Load Test |
| .lob | IBM DB2 LOBFILE |
| .loc | Localisation String Resource Header Format |
| .local | Delphi User-specific Project Options |
| .localized | MAC OS X |
| .localstorage | WebKit Local Storage Data Format |
| .localstorage-journal | Google Chrome Rollback Journal |
| .lock | Lock Format |
| .lock3 | BlackBerry Encrypted 3GP |
| .lockfile | Mac OS X Lion Property List XML Lock Format |
| .lock_sync | Synchronization Lock |
| .lod | Homeworld Level Of Detail Format |
| .lof | Audacity File List |
| .log | Log Format |
| .log1 | Microsoft Windows Registry Hive Log Format |
| .log2 | Microsoft Windows Registry Hive Log 2 Format |
| .logic | Apple Logic Pro Music Project Format |
| .logikcs | Apple Logic Key Commands |
| .login | UNIX Command |
| .logonvista | Stardock LogonStudio Windows Vista Logon Screen Format |
| .logonxp | LogonStudio Document Format |
| .lok | W32/Rbot-WE Log |
| .lol | Lolcode Source Format |
| .lols | LOLCODE Source Code |
| .lon | Aquaterra Profile Data |
| .look | SpeedGrade Look Format |
| .loop | Apple Soundtrack Pro |
| .loov | Smadav Virus Definitions Format |
| .lop | MasterCook Layout Format |
| .los | Close Combat 2 Map Related |
| .lot | LaTex Auxiliary File For List Of Tables |
| .lov | SAP Business Objects |
| .love | LÖVE Game Package Format |
| .lo_ | Microsoft System Management Server Renamed Old Log |
| .lp | Lightscape 3D Object Format |
| .lp2 | ILEAP Word Processor Document Format |
| .lp4 | 36-Image Converter Encrypted Language Pack |
| .lp7 | LP7Signer Digital Signed Format |
| .lpa | LPA View Laser Particle Analyser |
| .lpaq8 | PAQ Data Archive |
| .lpb | LaserTank Game Replay Format |
| .lpd | Lookout Protocol Driver Format |
| .lpdb | Librarian Pro Database Format |
| .lpdf | Mac OS X Localized PDF (Portable Document Format) Format |
| .lpf | Orgadata LogiKal |
| .lpi | Free Pascal Lazarus Project Information |
| .lpk | ArcGIS Layer Package Format |
| .lpmd | Las Palmeras Molecular Dynamics (LPMD) Data Format |
| .lpn | LVPLAN |
| .lpp | LabelPrint Project Format |
| .lpr | Homeworld |
| .lproj | Mac OS X Localized Project Folder Format |
| .lps | Bryce Leaf Shape Format |
| .lpt | LogPlot Compiled Boring Log |
| .lpu | Passolo Localization Project |
| .lpw | IRIS Laserform Lforms |
| .lpx | LaTeXPiX Script |
| .lqf | LeechFTP Save Queue |
| .lqr | SQ Compressed LBR Archive |
| .lqt | Liquid Audio Liquid Digital Media Music File Format |
| .lr | Chaos Desktop Layer List |
| .lrc | Lyric Format |
| .lrcat | Adobe Lightroom Catalog Format |
| .lrcat-journal | Adobe Photoshop Lightroom |
| .lrd | Microsoft Money Lock |
| .lrdata | Adobe Lightroom Preview Data |
| .lrdb | Photoshop Lightroom Database |
| .lrec | Inter-Tel Web Conference Recording Format |
| .lrf | BBeB Ebook Format |
| .lrg | Macromedia XRes Multi-resolution Bitmap |
| .lrl | SmartWare Local Resource Library |
| .lrm | Microsoft Encarta Class Server Learning Resource |
| .lrn | Apple Chess User Data |
| .lrp | IBM Works For OS/2 Report |
| .lrplugin | Adobe Photoshop Lightroom Plug-in Format |
| .lrprev | Adobe Photoshop Lightroom Index |
| .lrs | BBeB Ebook Source Format |
| .lrsmcol | Adobe Photoshop Lightroom Settings Format |
| .lrtemplate | Adobe Photoshop Lightroom Preset Settings Format |
| .lrtoolkit | Adobe Photoshop Lightroom |
| .lrv | Low Resolution Video Format |
| .lrwebengine | Lightroom Folder |
| .lrx | BBeB Ebook Format |
| .lry | Konica Minolta Data Management Software Reference Data |
| .ls | LightWave LScript Format |
| .ls1 | Microsoft Winhelp Source |
| .ls3 | Band-in-a-Box Style Format |
| .ls4 | Lumion Exported Full Scene |
| .lsa | Lotus Designer Agent |
| .lsaprototype | Microsoft Visual Studio Logical Datacenter Diagram Toolbox Prototype |
| .lsc | LOGO! Soft Comfort |
| .lsd | FIFA World Cup Game Data Environment Format |
| .lsf | Advanced Streaming Format |
| .lsl | Corel Paradox Format |
| .lslibrary | Littlesnapper User Library Package |
| .lsm | Ziess LSM Model |
| .lsn | Microsoft Works Format |
| .lso | Apple Logic Song Format |
| .lsp | LISP Source Code Format |
| .lsproj | Visual Studio LightSwitch Project |
| .lsq | IBM Voice Type Languages Addword |
| .lsr | LANsurveyor Report Format |
| .lss | LotusScript Source Code |
| .lst | List Text Format |
| .lstx | E-Sword Verse List |
| .lsu | LANsurveyor Map Format |
| .lsv | Light-O-Rama Sequence Editor Visual Preference |
| .lsw | RPG Maker Saved Game Format |
| .lsx | Advanced Streaming Redirector Format |
| .lsz | Learning Score Zip |
| .ls_ | Unix Ls Directory |
| .lt2 | Poser Light Set Format |
| .lta | Monolith Lithtech Game Engine |
| .ltb | Amma Little Setup Builder |
| .ltc | LTC Syntactically Analyzed Text |
| .ltcx | LTC Syntactically Analyzed Text XML |
| .ltd | LivingTime Data |
| .ltf | Frogans Short-cut Format |
| .ltg | LaserTank Graphics Format |
| .lth | Roxio Label Creator Style |
| .ltkey | LeaderTask Key |
| .ltl | DIALux Luminaire Data |
| .ltm | IBM Lotus Forms Form |
| .ltr | Letter Format |
| .lts | Links Email Tourney |
| .ltt | HP Library And Tape Tools Log |
| .ltx | LaTeX Document Format |
| .ltz | Poser Compressed Light Set Format |
| .lua | Lua Script Format |
| .luac | Lua Compiled Source Code |
| .luar | UltraDefrag Lua Report |
| .luca | Luca Template |
| .lucs | Amaya Tools |
| .lud | CARE-S InfoWorks Land Use |
| .lue | Norton LiveUpdate Log Format |
| .luf | Lipikar Uniform Format |
| .lug | Game |
| .lum | Luminous Song List |
| .lut | XnView Lut Format |
| .lutx | RadioRA Essentials Database Format |
| .luv | Medieval 2 Total War |
| .luxb | Lux Delux Map Format |
| .luz | Spectramap |
| .lv6 | Return To Wonderland Level |
| .lva | Logitech Video Effects Avatar Format |
| .lvb | Outlaws Game |
| .lvclass | LabVIEW Class Library |
| .lvd | LabelPro Design Document |
| .lvf | Logitech Video Effects Avatar And Face Accessory |
| .lvivt | Lvivtotoro Game Format |
| .lvix | Lightworks Video Index |
| .lvl | Game Level Format |
| .lvlib | LabVIEW Project Library |
| .lvlibp | LabVIEW Packed Project Library |
| .lvlps | LabVIEW Local Project Settings |
| .lvm | LabVIEW Measurement Format |
| .lvp | Avaya Voice Player Compressed Voice Audio |
| .lvr | Microsoft Visual Studio Environment Snapshot |
| .lvw | Livewire Document Format |
| .lw | LightWave 3D Binary |
| .lw2 | Lightwright Show Data |
| .lw3 | Lightwright Data |
| .lw4 | Lightwright 4 Show Data Format |
| .lw5 | Lightwright Show Data |
| .lwa | Lightwright Automated Action |
| .lwac | Likno Web Accordion Builder |
| .lwbm | Likno Web Button Maker |
| .lwc | Legacy Charting Chart |
| .lwd | LotusWorks Text Document |
| .lwf | LuraWave Format Image Format |
| .lwfn | Adobe Type 1 Font |
| .lwi | Light Work Image Image Format |
| .lwk | Siemens NX Software Graphics |
| .lwl | Lightwright Printed Paperwork Formatting Instructions |
| .lwlo | LightWave Layered Object |
| .lwm | LittleWays Map |
| .lwmw | Likno Web Modal Windows Builder |
| .lwo | LightWave Object Format |
| .lwob | LightWave 3D Object |
| .lwp | Lotus Word Pro Document Format |
| .lwpp | Live Wallpaper For Mac Desktop Theme |
| .lwq | SWAT Lake Water Quality Input |
| .lws | LightWave Scene Format |
| .lwt | Lightwright Attribute List |
| .lwtb | Likno Web Tabs Builder |
| .lwtp | LimeWire Theme Format |
| .lwtt | Likno Web Tooltips Builder |
| .lwv | Microsoft Linguistically Enhanced Sound Format |
| .lwx | Lightwright Database |
| .lwz | LightWave 3D Plugin |
| .lxa | Microsoft Speech Engines Lexicon Format |
| .lxcp | LCARS X32 For Windows Color Profile Format |
| .lxd | EDictionary Reader Dictionary Data |
| .lxf | LEGO CAD Scene Format |
| .lxfml | LEGO Digital Designer XML Format |
| .lxk | COREX Lexicon Link-up |
| .lxl | Luxology Modo Single-layer Mesh Presets |
| .lxo | Luxology Modo 302 3D Drawing Format |
| .lxsopt | Liquid XML Studio Project Settings Format |
| .lxsproj | Liquid XML Studio Project Format |
| .lxt | S.T.A.L.K.E.R. |
| .lxv | Lexar Secure II Encrypted Archive |
| .ly | LilyPond Music Score Format |
| .lyc | BestIMAGE Compressed Drawing Format |
| .lyr | ArcView Layer Format |
| .lys | DataCAD Layer Control |
| .lyt | DESQview Format |
| .lyx | LyX Document Format |
| .lz | LZIP Compressed Archive Format |
| .lzc | Need For Speed Undercover Game Data |
| .lzf | Autodesk 3D Studio Max Lens Effect Flare |
| .lzh | LH ARC Compressed Archive Format |
| .lzk | LoizziTimeControl Database |
| .lzm | Slax Module Format |
| .lzma | 7-zip Compressed Format |
| .lzma86 | Archive |
| .lzo | Lzop Archive Format |
| .lzop | LZOP Compressed |
| .lzp | Law And Order 3: Justice Is Served Game |
| .lzs | Compressed File Archive |
| .lzx | Amiga LZX Archive Format |
