| .LFM | Interscape | Arquivos de dados | LifeForm Data | Life Form Studio | Interscape |
| .LFP | Ipro Tech | Arquivos de dados | IPRO LFP File | IPRO Tech iConvert | Ipro Tech |
| .LGA | Microsoft Corporation | Arquivos de dados | Microsoft Windows Application Log File | Microsoft Windows | Microsoft Corporation |
| .LGB | Intuit, Inc. | Arquivos de dados | QuickBooks Little Green Box | QuickBooks | Intuit, Inc. |
| .LGC | Microsoft Corporation | Arquivos de dados | Microsoft Windows Application Log File | Microsoft Windows | Microsoft Corporation |
| .LGD | Microsoft Corporation | Arquivos de dados | Microsoft Windows Application Log File | Microsoft Windows | Microsoft Corporation |
| .LGE | Don Ho | Arquivos de dados | Log Data | Microsoft Notepad | Microsoft Corporation |
| .LGF | Microsoft Corporation | Arquivos de dados | Microsoft Windows Application Log File | Microsoft Windows | Microsoft Corporation |
| .LGG | Microsoft Corporation | Arquivos de dados | Microsoft Windows Application Log File | Microsoft Windows | Microsoft Corporation |
| .LGH | Microsoft Corporation | Arquivos de dados | Microsoft Windows Application Log File | Microsoft Windows | Microsoft Corporation |
| .LGI | Softronics Inc. | Arquivos de dados | Multimedia Logic File | MultiMedia Logic | Softronics Inc. |
| .LGJ | Microsoft Corporation | Arquivos de dados | Microsoft Windows Application Log File | Microsoft Windows | Microsoft Corporation |
| .LGL | Open Source | Arquivos de dados | LeechGet Download List | LeechGet | Open Source |
| .LGM | Microsoft Corporation | Arquivos de dados | Microsoft Windows Application Log File | Microsoft Windows | Microsoft Corporation |
| .LGN | Microsoft Corporation | Arquivos de dados | Microsoft Windows Application Log File | Microsoft Windows | Microsoft Corporation |
| .LGP | Microsoft Corporation | Arquivos de dados | Microsoft Windows Application Log File | Microsoft Windows | Microsoft Corporation |
| .LGS | Microsoft Corporation | Arquivos de dados | Microsoft Windows Application Log File | Microsoft Windows | Microsoft Corporation |
| .LGU | Microsoft Corporation | Arquivos de dados | LG Windows CE Upgrade Data | Microsoft Windows CE Embedded | Microsoft Corporation |
| .LGV | Microsoft Corporation | Arquivos de dados | Debugging Tools For Windows Logger Log | Debugging Tools for Windows | Microsoft Corporation |
| .LHP | Electric Butterfly, Inc. | Arquivos de dados | Lighthouse Organizer Data | Lighthouse Organizer | Unknown Developer |
| .LHR | Intuit, Inc. | Arquivos de dados | Quicken Financial Life For Mac Financial Data | Quicken Essentials for Mac | Intuit, Inc. |
| .LHX | GridSense | Arquivos de dados | LineTracker Firmware Upgrade | LineMan Remote | GridSense |
| .LIA | Altium | Arquivos de dados | P-CAD Schematics Library | P-CAD | Altium |
| .LIB | Various Developers | Arquivos de dados | Generic Data Library | Unknown Software | Unknown Developer |
| .LICENSE | Unknown Developer | Arquivos de dados | Generic License File | Microsoft Visual Studio | Microsoft Corporation |
| .LIF | The LEGO Group | Arquivos de dados | LEGO Digital Designer Assets File | LEGO Digital Designer | The LEGO Group |
| .LIFE | Light of Creativity, Inc. | Arquivos de dados | Light Notebook File | Light Notebook | Light of Creativity, Inc. |
| .LIN | Autodesk, Inc. | Arquivos de dados | AutoCAD Linetype File | Autodesk AutoCAD | Autodesk, Inc. |
| .LINUX | Open Source | Arquivos de dados | Linux Data File | FreeBSD | The FreeBSD Community |
| .LIST | Open Source | Arquivos de dados | APT List File | Advanced Package Tool (APT) | Open Source |
| .LISTING | Apple | Arquivos de dados | Golden Orchard Apple II CD Rom File | Apple OS X | Apple |
| .LIV | Cantoche | Arquivos de dados | Living Actor Actor File | Living Actor | Cantoche |
| .LIVEREG | Symantec Corporation | Arquivos de dados | Symantec Antivirus Session File | Symantec LiveReg | Symantec Corporation |
| .LIVEUPDATE | Symantec Corporation | Arquivos de dados | Symantec LiveUpdate File | Norton SystemWorks | Symantec Corporation |
| .LIX | Interscape | Arquivos de dados | Logos Library System File | Logos Bible Software | Interscape |
| .LK | Revelation Software | Arquivos de dados | Primary Data Storage Space | OpenInsight | Revelation Software |
| .LKB | Faiveley Transport Group | Arquivos de dados | Faiveley Data Recorder File | Bach-Simpson Event Recorders | Faiveley Transport Group |
| .LKO | Microsoft Corporation | Arquivos de dados | Outlook Express Linked Object | Microsoft Outlook Express | Microsoft Corporation |
| .LKP | Microsoft Corporation | Arquivos de dados | Microsoft Systems Management Server (SMS) Data | Microsoft Systems Management Server | Microsoft Corporation |
| .LKR | Microchip Technology Inc. | Arquivos de dados | MPLAB Linker Data | MPLAB C Compiler | Microchip Technology Inc. |
| .LKS | Captel SARL | Arquivos de dados | Offline Liberkey Packages | LiberKey | Captel SARL |
| .LLB | National Instruments | Arquivos de dados | LabVIEW Library File | LabVIEW | National Instruments |
| .LLF | Unknown Developer | Arquivos de dados | IITM Local Language Data | IITM | Unknown Developer |
| .LLV | Locklizard | Arquivos de dados | Lizard Safeguard License | Lizard Safeguard PDF Security | Locklizard |
| .LMD | ABBYY | Arquivos de dados | Abbyy Finereader Sprint File | ABBYY FineReader | ABBYY |
| .LMH | Open Source | Arquivos de dados | Memory Hacking Software Memory File | Memory Hacking Software | Open Source |
| .LMR | Intuit, Inc. | Arquivos de dados | QuickBooks Loan Manager Data | QuickBooks | Intuit, Inc. |
| .LMT | ENTERBRAIN, INC. | Arquivos de dados | RPG Maker 2000/2003 Map Tree | RPG Maker VX | ENTERBRAIN, INC. |
| .LMX | Nokia | Arquivos de dados | Landmark Exchange File | Nokia PC Suite | Nokia |
| .LNB | Mike Bradley | Arquivos de dados | Logomanager File | LogoManager | Mike Bradley |
| .LNF | Open Source | Arquivos de dados | Oyoaha Lookandfeel Interface Elements File | oyoaha lookandfeel | Open Source |
| .LNG | Nullsoft | Arquivos de dados | Winamp Language File | Nullsoft Winamp | Nullsoft |
| .LNGX | Dominik Reichl | Arquivos de dados | KeePaas Language Data | KeePass Password Safe | Open Source |
| .LNM | Corel | Arquivos de dados | Corel WordPerfect SGML Alias File | Corel WordPerfect | Corel |
| .LNS | AVG Technologies | Arquivos de dados | AVG Anti-Virus Language Data File | AVG Antivirus | AVG Technologies |
| .LNT | Gimpel Software | Arquivos de dados | PC-lint/FlexeLint Configuration File | Microsoft Notepad | Microsoft Corporation |
| .LOAD | Apple | Arquivos de dados | Golden Orchard Apple II CD Rom File | Apple OS X | Apple |
| .LOADER | Apple | Arquivos de dados | Golden Orchard Apple II CD Rom File | Apple OS X | Apple |
| .LOAN | Apple | Arquivos de dados | Golden Orchard Apple II CD Rom File | Apple OS X | Apple |
| .LOC | TopoGrafix | Arquivos de dados | GPS Location File | EasyGPS | TopoGrafix |
| .LOCAL | Embarcadero Technologies | Arquivos de dados | Delphi User-Specific Project Options | Delphi (IDE) | Embarcadero Technologies |
| .LOCALSTORAGE | Google | Arquivos de dados | WebKit Local Storage Data File | Google Chrome | Google |
| .LOG | Unknown Developer | Arquivos de dados | Log File | Microsoft Notepad | Microsoft Corporation |
| .LOGO | Apple | Arquivos de dados | Golden Orchard Apple II CD Rom File | Apple OS X | Apple |
| .LOGON | Unknown Developer | Arquivos de dados | Unknown Apple II File. (found On Golden Orchard Apple II CD Rom) | Atom | GitHub, Inc. |
| .LOT | Leslie Lamport | Arquivos de dados | LaTeX List Of Tables | LaTex | Leslie Lamport |
| .LP1 | Apple | Arquivos de dados | Golden Orchard Apple II CD Rom File | Apple OS X | Apple |
| .LP7 | Lex Persona | Arquivos de dados | LP7 Digital Signed File | LP7Creator | Lex Persona |
| .LPA | MP Filtri | Arquivos de dados | LPA View Laser Particle Analyser Data | LPA View | MP Filtri |
| .LPD | GNU Project | Arquivos de dados | LPD Daemon Print Permissions File | Vim | Bram Moolenaar |
| .LPF | Orgadata AG | Arquivos de dados | Orgadata LogiKal File | LogiKal | Orgadata AG |
| .LPI | Unknown Developer | Arquivos de dados | Laser Printer Information | Unknown Software | Unknown Developer |
| .LPJ | Interscape | Arquivos de dados | LIMDEP Project | LIMDEP | Interscape |
| .LPK | ESRI | Arquivos de dados | ArcGIS Layer Package | ESRI ArcGIS for Desktop | ESRI (Environmental Systems Research Institute) |
| .LPN | n.v. Systems Europe s.a. | Arquivos de dados | LVPLAN Data | LVPLAN | n.v. Systems Europe s.a. |
| .LPP | CyberLink | Arquivos de dados | LabelPrint Project File | CyberLink LabelPrint 2.5 | CyberLink |
| .LPS | DAZ 3D | Arquivos de dados | Bryce Leaf Shape File | DAZ 3D Bryce | DAZ 3D |
| .LPT | Interscape | Arquivos de dados | LogPlot Compiled Boring Log File | LogPlot | Interscape |
| .LQ | Unknown Developer | Arquivos de dados | Unknown Apple II File. (found On Golden Orchard Apple II CD Rom) | Atom | GitHub, Inc. |
| .LQA | Vernier Software & Technology | Arquivos de dados | Logger Pro Automatic Update | Vernier Logger Pro | Vernier Software & Technology |
| .LQF | Open Source | Arquivos de dados | LeechFTP Saved Queue | LeechFTP | Open Source |
| .LQM | LG Electronics | Arquivos de dados | LG QuickMemo Note | LG QuickMemo | LG Electronics |
| .LQP | Liquid Audio Inc | Arquivos de dados | Liquid Audio Player Passport Data | Liquid Audio Player | Liquid Audio Inc |
| .LQU | LeapWare | Arquivos de dados | LeapFTP Queue Data | LeapFTP | LeapWare |
| .LR | Adtollo | Arquivos de dados | Chaos Desktop Layer List File | Chaos desktop | Adtollo |
| .LRM | Microsoft Corporation | Arquivos de dados | Encarta Class Server Learning Resource File | Microsoft Encarta | Microsoft Corporation |
| .LRT | Aequus Gaming LTD | Arquivos de dados | League Of Legends Replay File | LOLReplay | Aequus Gaming LTD |
| .LRV | Konica Minolta | Arquivos de dados | Konica Minolta Data Management Software Stored File | Konica Minolta Data Management Software | Konica Minolta |
| .LSD | ENTERBRAIN, INC. | Arquivos de dados | RPG Maker Game Save File | RPG Maker VX | ENTERBRAIN, INC. |
| .LSF | Interscape | Arquivos de dados | Logos Library System File | Logos Bible Software | Interscape |
| .LSI | Hewlett-Packard | Arquivos de dados | Xerox Lightscribe Label | LightScribe Template Labeler | Hewlett-Packard |
| .LSL | Corel | Arquivos de dados | Corel Paradox File | Corel Paradox | Corel |
| .LSP | Open Source | Arquivos de dados | Lisp Program Source Code File | MacroMates TextMate | MacroMates |
| .LSQ | IBM | Arquivos de dados | IBM Voice Type Languages Addword Data | IBM Voice Type | IBM |
| .LSR | SolarWinds Inc. | Arquivos de dados | LANsurveyor Report | LANsurveyor | SolarWinds Inc. |
| .LST | Unknown Developer | Arquivos de dados | Data List | LibreOffice | The Document Foundation |
| .LT | Andrew Jewett | Arquivos de dados | Moltemplate Data File | Moltemplate | Andrew Jewett |
| .LTD | Lifescope Inc | Arquivos de dados | LivingTime Data File | LivingTime | Lifescope Inc |
| .LTM | IBM | Arquivos de dados | IBM Lotus Forms Form | IBM Lotus Forms Viewer | IBM |
| .LTT | Hewlett-Packard | Arquivos de dados | HP Library And Tape Tools Log | Notepad++ | Don Ho |
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