| .K02 | SoftVelocity | Arquivos de dados | Clarion Data File | Clarion | SoftVelocity |
| .K2 | Data Access Worldwide | Arquivos de dados | DataFlex Index | DataFlex | Data Access Worldwide |
| .K4 | Data Access Worldwide | Arquivos de dados | DataFlex Index | DataFlex | Data Access Worldwide |
| .K7 | Data Access Worldwide | Arquivos de dados | DataFlex Index | DataFlex | Data Access Worldwide |
| .KAD | Native Instruments | Arquivos de dados | Kore User Data | Kore | Native Instruments |
| .KAL | Kratos Analytical | Arquivos de dados | Kratos Vision Data File | CasaXPS | Casa Software Ltd |
| .KAN | Open Source | Arquivos de dados | Kwalitan Annotation | Kwalitan | Open Source |
| .KAP | Maptech | Arquivos de dados | BSB Chart Image File | Maptech U.S. Boating Charts | Maptech |
| .KAS | Evil Laboratories | Arquivos de dados | Karaoke File | EvilLyrics | Evil Laboratories |
| .KBD | Autodesk, Inc. | Arquivos de dados | 3ds Max Keyboard Shortcuts File | Autodesk 3ds Max | Autodesk, Inc. |
| .KBF | Milenix Software Ltd. | Arquivos de dados | MyInfo Document | MyInfo | Milenix Software Ltd. |
| .KBI | Derek Hendrikz | Arquivos de dados | Keirsey-Bates Temperament Sorter Index | Keirsey-Bates Temperament Sorter | Keirsey Group |
| .KBK | Unknown Developer | Arquivos de dados | Medeco XT Codebooks For Keys Data | Unknown Software | Unknown Developer |
| .KBN | TeamSpeak Systems | Arquivos de dados | TeamSpeak Keybinding File | TeamSpeak | TeamSpeak Systems |
| .KBR | Unknown Developer | Arquivos de dados | Keirsey-Bates Temperament Sorter Data | Unknown Software | Unknown Developer |
| .KBS | PC Dirck | Arquivos de dados | Keyboard Script File | PC Dirck Keyboard Script | PC Dirck |
| .KBX | GNU Project | Arquivos de dados | GNU Privacy Guard Keybox File | GNU Privacy Guard | GNU Project |
| .KCD | Symantec Corporation | Arquivos de dados | Rshiphop.kcd Malware | Avira Antivirus Pro 2016 | Avira Operations GmbH & Co. KG. |
| .KCL | Nintendo | Arquivos de dados | Mario Kart Collision File | Mario Kart Wii | Nintendo |
| .KCM | MM. Sys Bt. | Arquivos de dados | KönyvCalc File | KönyvCalc | MM. Sys Bt. |
| .KCX | Kea Software | Arquivos de dados | Kea Coloring File | Kea Coloring Book | Kea Software |
| .KD3 | Yayoi Co., Ltd. | Arquivos de dados | Yayoi Kaikei Accounting Data | Yayoi Accounting | Yayoi Co., Ltd. |
| .KDBX | Dominik Reichl | Arquivos de dados | KeePass Password Database | KeePass Password Safe | Open Source |
| .KDC | Kaspersky Lab | Arquivos de dados | Kaspersky Virus Database File | Kaspersky Anti-Virus | Kaspersky Lab |
| .KDF | Kinko's | Arquivos de dados | Kinko's File Prep Tool Data | Kinko's File Prep Tool | Kinko's |
| .KDS | Knyzhov Dmitry | Arquivos de dados | KD Player Skin File | Microsoft Notepad | Microsoft Corporation |
| .KDT | National Technical University of Athens | Arquivos de dados | Medbasin Evaporation Data | Medbasin | National Technical University of Athens |
| .KDZ | Kaspersky Lab | Arquivos de dados | Kaspersky Virus Bases File | Kaspersky Anti-Virus | Kaspersky Lab |
| .KEA | Panasonic Corporation | Arquivos de dados | Panasonic KTS File | Panasonic HD Writer AE | Panasonic Corporation |
| .KERNEL | Apple | Arquivos de dados | Golden Orchard Apple II CD Rom File | Apple OS X | Apple |
| .KEY | Unknown Developer | Arquivos de dados | License/ Encrypted Security Key File | Avira Antivirus Pro 2016 | Avira Operations GmbH & Co. KG. |
| .KEYNOTE | Apple | Arquivos de dados | iWork Keynote '06 Presentation | Apple Keynote | Apple |
| .KHF | Open Source | Arquivos de dados | Kwalitan Data File | Kwalitan | Open Source |
| .KID | Inspiration Software Inc. | Arquivos de dados | Kidspiration Document | Kidspiration | Inspiration Software Inc. |
| .KIF | Autodesk, Inc. | Arquivos de dados | AutoCAD Key Index File Format | Autodesk AutoCAD | Autodesk, Inc. |
| .KIK | Apple | Arquivos de dados | Golden Orchard Apple II CD Rom File | Apple OS X | Apple |
| .KIWI | Open Source | Arquivos de dados | KiwiViewer Scene | KiwiViewer | Open Source |
| .KJV | Costas stergiou | Arquivos de dados | TheWord Data | theWord | Costas stergiou |
| .KK2 | Payroll Associates, LLC | Arquivos de dados | ViewChoice | PayChoice | Payroll Associates, LLC |
| .KKT | TTS | Arquivos de dados | TTS-Kone File | TTS-Kone | TTS |
| .KKW | Adobe Systems Incorporated | Arquivos de dados | Adobe RoboHelp Keyword Help Project Index File | Adobe RoboHelp | Adobe Systems Incorporated |
| .KLA | Unknown Developer | Arquivos de dados | KLARFF Map Data | Unknown Software | Unknown Developer |
| .KLB | Software MacKiev | Arquivos de dados | KidPix Sticker, Stamp Album | Kid Pix | Software MacKiev |
| .KLF | Frank Böpple | Arquivos de dados | KaloMa Data | KaloMa | Frank Böpple |
| .KLG | Unknown Developer | Arquivos de dados | KOFIA Log | KOFIA | Unknown Developer |
| .KLI | Unknown Developer | Arquivos de dados | KalKulator Linear Algebra Data | Unknown Software | Unknown Developer |
| .KLIP | Klipfolio Inc. | Arquivos de dados | KlipFolio Klip | KlipFolio | Klipfolio Inc. |
| .KLK | Orgadata AG | Arquivos de dados | Orgadata LogiKal Data | LogiKal | Orgadata AG |
| .KLP | Phoenix Contact | Arquivos de dados | CLIP PROJECT Terminal-Strip Project | Clip Project | Phoenix Contact |
| .KLX | Sinasoft Co. | Arquivos de dados | Kelk 2000 Data | Kelk 2000 | Sinasoft Co. |
| .KM | BMC | Arquivos de dados | BMC Patrol Knowledge Module | BMC | BMC |
| .KM2 | KAISHA-Tec | Arquivos de dados | ActiveModeler Process Map | Avantage | KAISHA-Tec |
| .KMA | Correlate | Arquivos de dados | Correlate Archive File | Correlate | Correlate Client |
| .KMD | Open Source | Arquivos de dados | ABSTAT For Windows Batch File | ABstat | Open Source |
| .KMF | Open Source | Arquivos de dados | Kwalitan Memo File | Kwalitan | Open Source |
| .KMO | Unknown Developer | Arquivos de dados | Commercial Bank Czech Financial Data Exchange Format | Unknown Software | Unknown Developer |
| .KMS | Correlate | Arquivos de dados | Correlate Solutions File | Correlate | Correlate Client |
| .KMY | Open Source | Arquivos de dados | KMyMoney Data File | KMyMoney | Open Source |
| .KMZ | Google | Arquivos de dados | Google Earth Placemark File | ESRI ArcGIS for Desktop | ESRI (Environmental Systems Research Institute) |
| .KNB | Unknown Developer | Arquivos de dados | Neuro-Expert System Knowledge Base Data File | Neuro-Expert System | Unknown Developer |
| .KND | NEPLAN AG | Arquivos de dados | NEPLAN-DOS Import Or Export File | NEPLAN Electricity | NEPLAN AG |
| .KNF | Orchida Soft | Arquivos de dados | Orchida Knitting System Data | Orchida Knitting System | Orchida Soft |
| .KNO | EvREsearch LTD. | Arquivos de dados | DigIN Serialized Break Model | DigIN | EvREsearch LTD. |
| .KOC | Open Source | Arquivos de dados | Koha Offline Circulation Data | Koha | Open Source |
| .KOK | Recisio | Arquivos de dados | KaraFun Karaoke Data | KaraFun | Recisio |
| .KOS | South-Western Educational Publishing | Arquivos de dados | MicroType Pro Document File | MicroType Pro | South-Western Educational Publishing |
| .KPF | ActiveState | Arquivos de dados | Komodo Project File | ActiveState Komodo IDE | ActiveState |
| .KPP | Software MacKiev | Arquivos de dados | Kid Pix Presentation | Kid Pix | Software MacKiev |
| .KPR | Open Source | Arquivos de dados | KPresenter Presentation | KOffice | Open Source |
| .KPX | Software MacKiev | Arquivos de dados | Kid Pix Picture | Kid Pix | Software MacKiev |
| .KRB | SourceForge | Arquivos de dados | Pyke Knowledge Rule Base | Pyke | SourceForge |
| .KRC | Kra-Tronic Corporation | Arquivos de dados | Mouse And Key Recorder Macro File | Kra-Tronic Corporation Mouse and Key Recorder | Kra-Tronic Corporation |
| .KRF | SPARTA, Inc. | Arquivos de dados | DNSSEC-Tools Keyrec Data File | DNSSEC-Tools | SPARTA, Inc. |
| .KSA | Kubotek Corporation | Arquivos de dados | KeyCreator Settings Archive File | Kubotek USA KeyCreator | Kubotek Corporation |
| .KSM | Pfaff | Arquivos de dados | Pfaff Embroidery Design File Format | Embroidermodder 2 | Open Source |
| .KSP | Luxion | Arquivos de dados | Keyshot Package | Keyshot | Luxion |
| .KSW | Cosmic Patterns Software | Arquivos de dados | Kepler Workflow Document | Kepler | Cosmic Patterns Software |
| .KTE | Open Source | Arquivos de dados | Kite Design File | FoilMaker | Open Source |
| .KTH | Apple | Arquivos de dados | iWork Keynote Theme | Apple Keynote | Apple |
| .KTI | Kelvin TOP-SET | Arquivos de dados | Kelvin TOP-SET Investigator Data | Kelvin TOP-SET Investigator | Kelvin TOP-SET |
| .KTX | Open Source | Arquivos de dados | Kwalitan Data File | Kwalitan | Open Source |
| .KU | Open Source | Arquivos de dados | Knowledge Explorer Knowledge Representation Knowledge Unit | my Knowledge Explorer | Open Source |
| .KUF | K.Y.N.G | Arquivos de dados | K.Y.N.G Update Data | K.Y.N.G | K.Y.N.G |
| .KUU | K.Y.N.G | Arquivos de dados | K.Y.N.G Data File | K.Y.N.G | K.Y.N.G |
| .KVB | MSR Enterprises | Arquivos de dados | Klick-N-View Business Cards | Klick-N-View Business Cards | MSR Enterprises |
| .KVC | Open Source | Arquivos de dados | KVC | KVIrc | Open Source |
| .KW3 | Pacific Software Publishing, Inc. | Arquivos de dados | KanjiWORD Document File | KanjiWORD | Pacific Software Publishing, Inc. |
| .KWB | Open Source | Arquivos de dados | Kwalitan Work File | Kwalitan | Open Source |
| .KWL | KDE | Arquivos de dados | KWalletManager File | KWalletManager | KDE |
| .KWO | KeyWallet GbR | Arquivos de dados | KeyWallet Encrypted Password Storage | KeyWallet | KeyWallet GbR |
| .KWZ | Nintendo | Arquivos de dados | Flipnote Studio 3D Flipnote Data | Flipnote Studio 3D | Nintendo |
| .KXP | SoftKey | Arquivos de dados | KEY Home Gourmet Data | KEY Home Gourmet | SoftKey |
| .KY | Sage | Arquivos de dados | Peachtext List Manager File | Peachtext | Sage |
| .KYN | ESTsoft | Arquivos de dados | ALSee Thumbnail Cache | ALSee | ESTsoft |
| .KZB | Rightware | Arquivos de dados | Kanzi Studio Binary Data | Kanzi Studio | Rightware |
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