since 2000
Alphabetic File Extension List: o
The file extension list you requested is shown on this page. It loads as a table so please give it a moment as some of the lists are quite long. These lists contain basic information: the extension, the name of the program it works with, the specific function of the file, and the company that makes the program. Not all extensions have all of the data. Click on the extension of interest to see the detail page for that extension. Total extensions in this particular list: 633.
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| Extension | Information |
| O | 7-zip compressed data (Igor Pavlov) |
| O | Acrobat document (Adobe) |
| O | Arm Compiler compiled object (Arm) |
| O | Free Pascal compiled object (FPC Development Team) |
| O | GCC compiled object (Free Software Foundation) |
| O | Origin data (OriginLab) |
| O | Visual Studio compiled object (Microsoft) |
| O | Xcode compiled object (Apple) |
| O$$ | Output File |
| O$$ | Sprint Outfile |
| O01 | Typhoon Voice File |
| O1 | Free Pascal Object File for GO321v1 Platform (FPC Development Team) |
| O2C | Objects to See 3D File Format (mb Software AG) |
| O3 | Ozone Messenger Program Support Files (htmlland.net) |
| O3D | OMSI 2 (The Omnibus Simulator) 3D model |
| O3S | 3Shape Ortho System Dental Scan |
| O8O | Mediator5 Repositorytabs Vorlagen.006 File |
| O9 | Lenel OnGuard Agent configuration |
| OA | OpenAttestation Viewer Verifiable Documents |
| OAB | Outlook offline address book (Microsoft) |
| OADX | OA Sistemi Word Processor !nnovatio word processing |
| OAF | ETH Oberon Applet File |
| OAF | Flight Simulator Texture File (Microsoft Corporation) |
| OAF | Outrage Animation Rows |
| OARC | Optix Archive Bundle (mindwrap, inc.) |
| OARC | Optix Archive Manifest (mindwrap, inc.) |
| OAT | Android optimized runtime application (Open Handset Alliance) |
| OAZ | NetFax Manager OAZ Fax File |
| OB | ABF Outlook Backup Backup File (ABF software, Inc.) |
| OB | IMB LinkWay Object File |
| OB! | Orbit Downloader Incomplete Download (OrbitDownloader.com) |
| OB$ | Compressed OBJ (Microsoft Corporation) |
| OB1 | OzWin CompuServe E-mail/Forum Access Saved Outbox File |
| OB3 | ORTIM Zeit Data (ORTIM Industrial Engineering Deutschland GmbH) |
| OB3 | Outlook Backup Full Backup File (ABF software, Inc.) |
| OBA | Timespace X100 Digital Video Recorder Video File (Timespace Technology Ltd.) |
| OBB | Android Studio encrypted data archive (Google) |
| OBD | Binder document objects collection (Microsoft) |
| OBD | Oracle Forms online help file (Oracle) |
| OBE | Out Of Box Experience |
| OBE | System DLL Oobe File |
| OBF | OpenStreetMap GIS project file (Map) (OpenStreetMap Foundation) |
| OBI | Outlook Outlook RSS Subscription File (Microsoft) |
| OBJ | 3D Builder standard 3D object data file (Microsoft) |
| OBJ | 3ds MAX standard 3D object data file (Autodesk) |
| OBJ | Blender standard 3D object data file (Blender) |
| OBJ | Bryce standard 3D object data file (DAZ 3D) |
| OBJ | CADRazor standard 3D object data file (TITAN Algorithms) |
| OBJ | LightWave 3D standard 3D object data file (NewTek) |
| OBJ | Maya standard 3D object data file (Autodesk) |
| OBJ | MeshLab standard 3D object data file (ISTI - CNR) |
| OBJ | Photoshop standard 3D object data file (Adobe) |
| OBJ | Relocatable Object Module object file (Intel) |
| OBJ | The Advanced Visualizer geometry definition file (Wavefront) |
| OBJ | UVMapper standard 3D object data file (Stephen L Cox) |
| OBJ | Visual Studio source code/script file (Microsoft) |
| OBJECT | various software, including game engines and business applications Storing object data |
| OBK | Phone Manager phonebook data file (Oxygen Software) |
| OBK | SQLite database backup file (SQLite) |
| OBK | Ubi Soft Chessmaster Opening Book File |
| OBML | Opera Mini Saved Web Page (Opera Software ASA) |
| OBML16 | Opera Mini Opera Mini cache |
| OBN | Oberon-2 Module Source File |
| OBP | Bryce 3D object preset (DAZ) |
| OBPACK | ObjectBar Object Package (Stardock Corporation, Inc.) |
| OBR | C++ Object Browser Data File (Borland Software Corporation) |
| OBR | Objective Reference Document Link (Objective Corporation Limited) |
| OBS | ObjectScript Script |
| OBS | OzWin CompuServe E-mail/Forum Access Saved Outbox File |
| OBSKIN | ObjectBar Skin File (Stardock Corporation, Inc.) |
| OBT | Office Binder Template (Microsoft Corporation) |
| OBTHEME | ObjectBar Theme File |
| OBTHEME | ObjectBar Theme File (Stardock Corporation, Inc.) |
| OBV | ObjectScript Visual Interface |
| OBW | Superior Drummer 2.0 Superior Drummer 2.0 (TOONTRACK) |
| OBX | OpenBook OpenBook 8.0 Document File (Freedom Scientific, Inc) |
| OBX | Rational XDE (IBM) |
| OBZ | Office Binder Wizard (Microsoft Corporation) |
| OC8 | OrgCon 8 Organization (EcoMerc) |
| OC9 | OrgCon 9 Organization (EcoMerc) |
| OCA | Visual Studio custom control library/cache (Microsoft) |
| OCB | Origin Precompiled Origin C File (OriginLab Corporation) |
| OCC | DB/TextWorks indexed records database file (Lucidea) |
| OCC | OptControlCentre model file |
| OCD | OCAD Digitized Map (Steinegger Software) |
| OCD | OrgCon 7 Organization (EcoMerc) |
| OCDF | OneClickdigital mp3 audio book file (Recorded Books) |
| OCE | Brio Query (Hyperion Solutions Corporation) |
| OCEN | EdGCM Data File (The EdGCM Cooperative Project of Columbia University) |
| OCF | Object Craft File |
| OCF | OM2Cipher File |
| OCI | openCanvas Image (System Products Co., Ltd.) |
| OCM | AOL Advertising Control File (America Online, Inc.) |
| OCM | Internet Odyssey 2 Update |
| OCM | Netscape Communicator Aim File |
| OCN | OneCable.net - Explorer Measurement Data File (OnTimeLine) |
| OCP | Advanced Art Studio |
| OCP | Offline Commander Project File |
| OCR | Notepad fax document (Microsoft) |
| OCR | Subtitle Workshop script (URUWorks) |
| OCS | eDoc DigiSign Digitally Signed Document (Fujitsu Denmark) |
| OCSP | Optix Scanner Plug-in (mindwrap, inc.) |
| OCSP-RESPONSE | OpenSSL Certificate Status Response |
| OCT | Octalizer musical data (Armin Sander) |
| OCT | Radiance 3D scene (Greg Ward) |
| OCTET-STREAM | web browsers, email clients, operating systems arbitrary binary data |
| OCX | Visual Studio custom control component (Microsoft) |
| OC_ | Doko Compressed Install File |
| OD | Mascopt graph request file (INRIA/UNSA) |
| OD1 | Omnis5 Database File |
| OD2 | Omnis5 Database File |
| OD3 | Omnis5 Database File |
| OD4 | Omnis5 Database File |
| OD5 | Omnis5 Database File |
| OD6 | Omnis5 Database File |
| OD7 | Omnis5 Database File |
| OD8 | Omnis5 Database File |
| OD9 | Omnis5 Database File |
| ODA | AIBO Audio Voice (Sony) |
| ODA | CALS Group IV Type 2 Raster Image |
| ODA | ODA Document |
| ODA | Used with OCX |
| ODB | Abaqus FEA model (Dassault Systèmes) |
| ODB | Allegro PCB Editor printed circuit board model (Cadence) |
| ODB | ArcGIS object database (ESRI) |
| ODB | Base database (Apache) |
| ODB | Base database (The Document Foundation) |
| ODB | Organizers Database database (Organizers' Collaborative) |
| ODB | Psion data (Psion) |
| ODC | Excel settings file (Microsoft) |
| ODC | OpenOffice Calc chart file (Apache) |
| ODCCUBEFILE | Office Data Connection |
| ODCDATABASEFILE | Office Data Connection |
| ODCNEWFILE | Office Data Connection |
| ODCTABLEFILE | Office Data Connection |
| ODD | Coby Voice Recorder Format (Coby Electronics Corp.) |
| ODE | Office Object Data Embedding File (Microsoft Corporation) |
| ODEX | Android optimized/pre-compiled app (Open Handset Alliance) |
| ODF | Battlezone object definition file (Activision) |
| ODF | LibreOffice Math mathematical equations file (Document Foundation) |
| ODF | OnkoS (OnkoS) |
| ODF | OpenOffice Math mathematical equations file (Apache) |
| ODF | Star Trek Armada object definition file (Activision) |
| ODG | Draw drawing (Apache) |
| ODG | Draw drawing (The Document Foundation) |
| ODG | Word drawing (Microsoft) |
| ODH | Odigo History File (Comverse, Inc. a part of Comverse Technology) |
| ODI | OpenOffice/StarOffice OpenDocument (Ver 2) Image (Sun Microsystems, Inc.) |
| ODIF | Open Document Interchange Format |
| ODL | Object Definition Language |
| ODL | Visual C++ Type Library Source (Interface Definition Language File) (Microsoft Corporation) |
| ODLGZ | Microsoft OneDrive OneDrive Log |
| ODLSENT | Microsoft OneDrive SyncEngine log file |
| ODM | Opendisc Software (Opendisc) |
| ODM | OpenOffice/StarOffice OpenDocument (Ver 2) Global Text Document (Sun Microsystems, Inc.) |
| ODM | OverDrive Media Console Media Control File (OverDrive Inc.) |
| ODMP | Optix Collection Package (mindwrap, inc.) |
| ODMZ | OnBase Document Archive |
| ODOCK | ObjectDock Theme (Stardock Corporation) |
| ODP | BIRT Analytics parameters and values file (Open Text) |
| ODP | LibreOffice Impress slideshow presentation file (Document Foundation) |
| ODP | Oedipus data and code file (Andrew M. Kuchling) |
| ODP | OpenOffice Impress slideshow presentation file (Apache) |
| ODP | PowerPoint slideshow presentation file (Microsoft) |
| ODR | OpenIV 3D Render Data |
| ODS | Calc spreadsheet (Apache) |
| ODS | Excel spreadsheet (Microsoft) |
| ODS | NCompass Resolution script (Microsoft) |
| ODS | Outlook Express mailbox (Microsoft) |
| ODS# | OpenOffice/StarOffice OpenDocument (Ver 2) Open Spreadsheet (Sun Microsystems, Inc.) |
| ODT | MindRender 3D virtual object (Themekit Systems) |
| ODT | Word document (Microsoft) |
| ODT | Writer document (Apache) |
| ODT | Writer document (The Document Foundation) |
| ODT | Writer document template (The Document Foundation) |
| ODU | Odigo User File (Comverse, Inc. a part of Comverse Technology) |
| ODX | BizTalk Server orchestration diagram file (Microsoft) |
| ODX-D | CANdelaStudio diagnostic data |
| ODZ | IBM OpenDoc Editor Package File |
| OEACCOUNT | Outlook Express Email Account Settings |
| OEB | eBook backup file (Open eBooks) |
| OEB | Outlook Express Backup Wizard (QSX Software Group) |
| OEM | Windows settings file (Microsoft) |
| OF | Audio Utility Tuningwrench Compressed File |
| OF | LessDATA Video System OneFile File |
| OF | MicroImages Outline Font (MicroImages, Inc.) |
| OF1 | Camtasia Studio video project |
| OFC | Open Financial Connectivity File |
| OFD | 20-20 Office Sales E-magine File (20-20 Technologies) |
| OFD | ObjectView Form Defintion |
| OFD | OfficeForms Form Data File (Toplevel Computing) |
| OFF | GLC_Player 3D object geometry definitions (GLC_Player Developer community) |
| OFIG | GNU Octave Saving plots |
| OFL | OtsTurntables Playlist (Ots Labs) |
| OFL_EN | Font Management Software Offline Font License |
| OFM | DesignShop embroidery instructions file (Melco) |
| OFM | Font Development Kit font description file (Adobe) |
| OFM | OfficeForms blank form file (Toplevel) |
| OFM | OmniForm form file (Nuance) |
| OFN | Office FileNew File (Microsoft Corporation) |
| OFN | Systems Management Server (SMS) Offer Creation Notification (Microsoft Corporation) |
| OFR | OptimFROG Encoded Audio (Florin Ghido) |
| OFR | Systems Management Server (SMS) Offer Description File (Microsoft Corporation) |
| OFT | Microsoft Outlook email template file (Microsoft) |
| OFW | Toplevel Forms Form (Toplevel Computing Ltd) |
| OFX | Microsoft Money financial data file (Microsoft) |
| OFX | MoneyDance financial data file (Infinite Kind) |
| OFX | Quicken financial data file (Quicken) |
| OFX | XnView MP fax image file (XnSoft) |
| OGA | Ogg Vorbis Audio Profile (Xiph.Org Foundation) |
| OGF | Descent 3 graphics rows (Interplay) |
| OGF | OGF Viewer 3D mesh and animation data (mrnotbadguy) |
| OGF | OnkoS graphics (OnkoS) |
| OGF | S.T.A.L.K.E.R 3D mesh and animation data (GSC) |
| OGF2 | MapViewGPS Map Coordinates File |
| OGF3 | MapViewGPS Map Coordinates File |
| OGG | Ogg Vorbis Codec Compressed Multimedia File (Xiph.Org Foundation) |
| OGG | Origin Graphic File (OriginLab Corporation) |
| OGG | Salt Lake City Game File |
| OGG_ | RPG Maker MV Game Audio |
| OGI | OpenPBX Gateway Interface File (OpenPBX.org) |
| OGL | Overlay Source Code |
| OGM | KMPlayer video (Pandora) |
| OGM | MPlayer video (Mplayer Team) |
| OGM | Origin matrix (OriginLab) |
| OGM | VLC video (VideoLAN) |
| OGNC | Web Page Source Code |
| OGO | Origin Pro Graphic Object File (OriginLab Corporation) |
| OGS | Origin Script File (OriginLab Corporation) |
| OGV | KMPlayer video (Pandora) |
| OGV | Media Player video (Microsoft) |
| OGV | VLC video (VideoLAN) |
| OGW | Origin Worksheet File (OriginLab Corporation) |
| OGX | C++ exported classes and resources (Borland) |
| OGX | Media Player multiplexed video (Microsoft) |
| OGX | VLC multiplexed video (VideoLAN) |
| OH | Overhoor ( DrillAssistant) List (Efkasoft) |
| OH4 | Overhoor ( DrillAssistant) List (Efkasoft) |
| OHC | OpenHelp Table of Contents File (Borland Software Corporation) |
| OHI | OpenHelp Index (Borland Software Corporation) |
| OHL | OpenHelp Link (Borland Software Corporation) |
| OHP | DOS 7 File |
| OHP | OpenHelp Project File (Borland Software Corporation) |
| OHS | Bink Outbound History |
| OHSD | HealthFrame OpenHealth Service Plug-in (Records For Living, Inc.) |
| OHW | Overhoor ( DrillAssistant) List (Efkasoft) |
| OI | P.I.S.D. Ltd Platform Library Baseball image files |
| OID | ProCurve Manager Non-ProCurve Network Device File (Hewlett-Packard Development Company, L.P.) |
| OID | Prosa/OM Object Interaction Diagram |
| OIF | QuickBase Web-sharable Database Interchange File |
| OIK | Lenné3D Plant Distribution File (Lenné3D GmbH i.G.) |
| OIL | Open Image Library Format |
| OIR | Olympus FluoView Microscope Image |
| OIT | SleepScan and Ceegraph Offset Index File (Bio-logic Systems Corp.) |
| OIV | OpenIV GTA V modding |
| OIX | Lenné3D Plant Distribution File (Lenné3D GmbH i.G.) |
| OJP | 3WayPack (The Three-Mode Company) |
| OK | Dot OK File Digest (John Oberschelp) |
| OKM | OkMap Map Defining File (Gian Paolo Saliola) |
| OKS | OKScript File (Mike Mardesich) |
| OKT | Oktalyzer Tracker Module |
| OKX | OKScript File (Mike Mardesich) |
| OL | Creo 3D model (PTC) |
| OL | Hammer 3D prefabs and object layout (Valve) |
| OLB | AUTOGEN |
| OLB | Medical Terminology Challenge data (Delmar Learning) |
| OLB | Office automation object library (Microsoft) |
| OLB | OpenVMS object library (VMS) |
| OLB | OrCAD PCB Designer symbol models library (Cadence) |
| OLB | PSpice symbol models library (Cadence) |
| OLD | Old Version |
| OLE | Object Linking and Embedding (OLE) Object |
| OLE2 | Microsoft Office Microsoft Office Binary Document Container Format file (Microsoft) |
| OLF | OyezForms Legal Documents (UK) (Oyez) |
| OLFX | OyezForms Conveyancing document |
| OLG | OATS Log File (AmsterCHEM) |
| OLI | Olivetti Text File |
| OLK | Microsoft Outlook for Mac address book file (Microsoft) |
| OLK14MESSAGE | Mac Outlook backup Mac Outlook backup (Mac Outlook) |
| OLK14MSGSOURCE | Mac Outlook backup Mac Outlook backup (Mac Outlook) |
| OLK15CONTACT | Microsoft Outlook Email contact data |
| OLK15EVENT | Microsoft Outlook Recurring Appointment Data |
| OLK15FOLDER | Microsoft Outlook Outlook folder index |
| OLK15MESSAGE | Mac Outlook backup Mac Outlook backup (Mac Outlook) |
| OLK15MSGATTACHMENT | Microsoft Outlook email attachment |
| OLK15MSGSOURCE | Mac Outlook backup Mac Outlook backup (Mac Outlook) |
| OLK15RECENTADDRESSES | Microsoft Outlook Recent Addresses |
| OLK15SEARCH | Microsoft Outlook Outlook Search Index |
| OLL | TrialDirector Load File (inData Corporation) |
| OLL | TrialDirector Object Load List |
| OLM | Microsoft Outlook database file (Microsoft) |
| OLN | Visual C++ Outline Examples (Microsoft Corporation) |
| OLR | Openlab Raw Format (Improvision) |
| OLRW | Openlab Raw Format (Improvision) |
| OLSR | olsrd Configuration (olsr.org) |
| OLT | Orbit Downloader List File (OrbitDownloader.com) |
| OLT | Visual C++ Outline Examples (Microsoft Corporation) |
| OLTS | Fiber optic testing and analysis software Fiber optic testing |
| OLV | OnLive! Traveler Sound File (The Digital Space Commons) |
| OLV | OyezForms Legal Documents (UK) (Oyez) |
| OM | Omicron Compiler File |
| OMA | Sony OpenMG Music Format File (Sony Corporation of America) |
| OMB | Omnibus Offline Web Storage (Alfega Technologies, Inc.) |
| OMCS | Office Manager Enterprise Document Archive (Softwarebuero Krekeler) |
| OMD | Prosa/OM Class Model |
| OMF | Open Media Format File |
| OMF | Operation, Management & Finance Database (ENIAC Computing) |
| OMFL | various software (Olympus cameras, WinZip, PDF viewers) Encrypted data storage |
| OMG | O&O DiskImage Disk Image (O&O Software GmBH) |
| OMG | OpenMG Jukebox (Sony) |
| OML | Onyx Graphics RipCenter Print Media Profiles |
| OMN | Omnipotent, Inc. Collection File |
| OMO | Oracle Media Objects File |
| OMOD | Oblivion Mod Manager Oblivion Mod Manager |
| OMP | Office Manager Pro Document Archive (Softwarebuero Krekeler) |
| OMP | OpenMind Project (MatchWare A/S) |
| OMS | Briggs Softworks Order Maven |
| OMS | Macintosh MP3 Music Format |
| OMS | Omega Downloader Configuration File |
| OMV | jamovi Data Analysis |
| OMX | OMAX Make Tool Path File (OMAX Corporation) |
| OMX | Ots Media Library (Ots Labs Pty Ltd) |
| ON | Audio Utility Tuningwrench Compressed File |
| ONC | Cisco AnyConnect Secure Mobility Client VPN connection settings |
| OND | Notes Database (IBM) |
| ONE | docPointer readme information file (docPointer) |
| ONE | EdgeCAM licensing data file (Hexagon) |
| ONE | OneNote note file (Microsoft) |
| ONE | SEMONE compressed archive file (Vladimir Semenjuk) |
| ONEPKG | OneNote data backup file (Microsoft Corporation) |
| ONETOC2 | OneNote OneNote Revision Store File (Microsoft) |
| ONF | Open Navigation Format File |
| ONLINE | Apple II operating system Golden Orchard Apple II CD Rom file |
| ONLINESADELES | WinZip Turkish Tax Declaration |
| ONLV | Dangl.Oenorm, A2063 LV-Editor Austrian Bill of Quantities |
| ONNX | machine learning frameworks (PyTorch, ONNX Runtime, etc.) model exchange |
| ONSE | SteuerGo German Tax Data |
| ONX | Onyx Graphics Postershop File |
| OO | Free Pascal Object File for OS/2 Version (FPC Development Team) |
| OOM | Shroom Swap File |
| OONN | Deep Learning Frameworks, Possibly Odoo Storing Neural Networks |
| OOP | OOP Packer Archive (TonyTown Software Ltd.) |
| OOSS | Ransomware (e.g., ooss ransomware) Encrypted Data |
| OP | Origin Preprocessed Origin C File (OriginLab Corporation) |
| OP | Rescue Disk File |
| OP2 | Musplay 1.72 File |
| OP2 | NEi Nastran Binary Results Neutral File (Noran Engineering, Inc.) |
| OP2 | Outpost 2 Saved Game |
| OP2 | Stanford Research Systems Optimlelt File (Stanford Research Systems, Inc.) |
| OPA | Psion OPL Object File (Psion PLC) |
| OPB | OpenPhone; Encryption Software; Opera Browser (rare) Call recordings; Encrypted data |
| OPC | Beta 44 Job File |
| OPC | Office Upgrade Control File (Microsoft Corporation) |
| OPC | Omron OPC Client File |
| OPD | Durango visualizations and supporting dataset file (Diffraction) |
| OPD | OmniPage page layout file (Kofax) |
| OPDOWNLOAD | Opera Browser Incomplete Downloads |
| OPENCERT | OpenCerts Verifier digital certificate file |
| OPENELEMENT | OpenElement Raster Image |
| OPENPGP_SIGNATURE | GnuPG / Kleopatra Digital Signature |
| OPF | Calibre open packaging format file (Kovid Goyal) |
| OPF | eBook Creator open packaging format file (Mobipocket) |
| OPF | eBook Publisher package file (Gemstar) |
| OPF | FlipAlbum digital album file (E-Book Systems) |
| OPF | FlipViewer flipbook metadata file (Revanton) |
| OPF | InDesign open packaging format file (Adobe) |
| OPF | KEPServerEX project configuration file (PTC) |
| OPF | Obsidium project save file (Obsidium) |
| OPF | Visual OMP project data file (DNA Software) |
| OPI | ExpressRecognition Server OCR Processing Information File (Adlib Software) |
| OPI | OmniPass Exported User (Softex, Inc.) |
| OPJ | OmniPage schedule (Nuance Communications) |
| OPJ | OrCAD PCB Designer PCB design project (Cadence) |
| OPJ | Origin project (OriginLab) |
| OPJU | OriginPro Data Analysis Project |
| OPK | Dragon UnPACKer game archive file (Alexandre Devilliers) |
| OPK | Origin archive file (OriginLab) |
| OPL | Psion Organiser Programming Language Source File (Psion PLC) |
| OPLUSDOWNLOAD | OnePlus Download Manager (ODM) Partially downloaded files |
| OPM | Quadrox Digital CCTV System Components |
| OPML | Feedly web feed outline (Feedly) |
| OPML | OmniOutliner web feed outline (The Omni Group) |
| OPN | Court Opinion File (Tennessee Administrative Office of the Courts) |
| OPN | Exact Active Options |
| OPN | Rebel Strip Poker Opponent File (Rebel Software) |
| OPN | Strip Poker Deluxe Opponent File (Eagle Rock Enterprises, Inc.) |
| OPO | Psion OPL Output Executable File (Psion PLC) |
| OPO | Psion Organiser OPL Code (Psion PLC) |
| OPOS | VirtuaSys Opos Script (VirtuaSys :: Sistemas Virtuais) |
| OPP | IPhoto File (Keronsoft) |
| OPPODOWNLOAD | OPPO Internet Browser Partially Downloaded File |
| OPQZ | Opus Encoder (likely a custom implementation or variation) Compressed, Encrypted Image |
| OPR | OPRO X Browser Print Report File (OPRO Japan Co.,Ltd.) |
| OPS | Adobe Acrobat (Adobe) |
| OPS | Dynamite VSP Object Placement Style (3am Solutions (UK) Limited) |
| OPS | Office Configuration file (Microsoft) |
| OPT | Business Integrator options (Pervasive Software) |
| OPT | CX-Programmer operating environment settings (OMRON) |
| OPT | Delphi project settings (options) (Embarcadero) |
| OPT | FLEXnet Manager options (Acresso) |
| OPT | MetaTrader optimization cache (MetaQuotes) |
| OPT | MySQL database options (Oracle) |
| OPT | pcAnywhere option set (NortonLifeLock) |
| OPT | PhotoScore document (Neuratron) |
| OPT | PowerMill CNC options (Autodesk) |
| OPT | ProWORX Nxt list module options (Schneider Electric) |
| OPT | Psion Organiser source code (Psion) |
| OPT | QEMM data (Quarterdeck Office Systems) |
| OPT | SilkTest option set (Segue) |
| OPT | Visual Studio workspace options (Microsoft) |
| OPTIONS | Google Chrome Store Chrome settings |
| OPUS | Apple II operating system Golden Orchard Apple II CD Rom file |
| OPW | OrgPlus Organization Chart (HumanConcepts, LLC) |
| OPX | FlipAlbum photo album and image metadata file (E-Book Systems) |
| OPX | Organization Chart organization chart file (Microsoft) |
| OPX | OrgPlus organization chart file (Insperity) |
| OPX | Origin installation data archive file (OriginLab) |
| OPY | OptiY Model (OptiY) |
| OQY | Excel OLAP Query File (Microsoft Corporation) |
| OR2 | Organizer Ver 2 File (IBM) |
| OR3 | Organizer 97 File (IBM) |
| OR4 | Organizer (IBM) |
| OR5 | Organizer (IBM) |
| OR6 | Organizer Data File (IBM) |
| OR8 | Rational Rose Oracle8 Database Model Report (IBM) |
| ORA | Instant Client network configuration parameters (Oracle) |
| ORA | Krita multi-layer image (Krita Foundation) |
| ORA | MyPaint multi-layer image (MyPaint Contributors) |
| ORC | cSound Synthesis Instruments (Csounders) |
| ORC | Digital Orchestrator Plus Sound File (Voyetra Turtle Beach, Inc.) |
| ORC | Oracle 7 Script |
| ORCA | Apple II operating system Golden Orchard Apple II CD Rom file |
| ORD | BC45 Owl File |
| ORD | OMAX Make Tool Path File (OMAX Corporation) |
| ORD | Open Reminder Database (ITOpen.eu SOFTWARE) |
| ORE | 3WayPack (The Three-Mode Company) |
| ORE | Narbacular Drop Game Content (DigiPen Corporation) |
| ORF | Descent 3 room description (Embracer) |
| ORF | Olympus Workspace raw image (Olympus) |
| ORF | PaintShop raw image (Corel) |
| ORF | Photoshop raw image (Adobe) |
| ORG | Emacs document data file (GNU Project) |
| ORG | Lotus Organiser organizer data file (IBM) |
| ORG | Odds Ratio Generator data file (Psytek) |
| ORG | Origin project data file (OriginLab) |
| ORG | Pinnacle Hollywood FX effects organizer data file (Corel) |
| ORG | Yamaha sound data file (Yamaha) |
| ORI | Need for Speed-Hot Pursuit 2 game data backup file (Electronic Arts Inc.) |
| ORI | Original |
| ORIG | Gen Original File |
| ORIGIN | Safari web browser Website referrer data |
| ORIGINAL | Netobjects Fusion Components BBScomp Message File |
| ORK | Warhammer: Mark of Chaos Game Archive (Games Workshop Group PLC) |
| ORKF | OCR Software Optimized Raster Images |
| ORM | Ormetis Workbench File (Ormetis S.A.S.) |
| ORMV | Ormetis View File (Ormetis S.A.S.) |
| ORO | 3WayPack (The Three-Mode Company) |
| ORV | Oracom Video Format (Oracom Co. Ltd.) |
| OS | Android application data (Open Handset Alliance) |
| OS | Apple DOS data (Apple) |
| OS | ObjectDevel object script (ObjectDevel Developer) |
| OS | SCons static library object (Scons Foundation) |
| OS3 | OS/2 Warp 3 File |
| OSA | W32/Sober-AD |
| OSAWDM | Optical Spectrum Analyzers (OSAs) Optical spectrum data |
| OSB | Sega Dreamcast Sound (One Shot Bank) (Sega of America, Inc.) |
| OSC | Formula One 2001 Options File |
| OSC | Fruitypro Samples SS_effects File |
| OSC | OptionScope Worksheet (Equis International) |
| OSC | Remote Installation Services Client Installation Wizard File (Microsoft Corporation) |
| OSD | Directory Opus Configuration File (GPSoftware) |
| OSD | Open Software Description File (Microsoft Corporation) |
| OSD | SoftGrid Program Description (Softricity, Inc.) |
| OSDX | Windows Search Connector (Microsoft Corporation) |
| OSF | Descent 3 Sound File (Outrage Entertainment) |
| OSF | Distribution Bin File |
| OSF | ICZ OriSAFE |
| OSF | Opera Skin (Opera Software ASA) |
| OSF | Virtual Ticket (MetaCommunications) |
| OSG | OpenSceneGraph ASCII Native Format (OSG Community) |
| OSGB | OpenSceneGraph CAD file (OpenSceneGraph Developers) |
| OSGJS | OpenSceneGraph 3D Scene Data |
| OSHEET | Online spreadsheet applications Spreadsheet data |
| OSI | Osiris Database (The Shmoo Group) |
| OSI | SunNet OSI Description File (Sun) |
| OSK | osu! osu! skin files |
| OSL | OckamSoft Log File (Ockam Instruments, Inc.) |
| OSM | OpenStreetMap GIS project file (Map) (OpenStreetMap Foundation) |
| OSP | On-Screen Takeoff bid package export (On Center) |
| OSP | OpenShot video project (OpenShot) |
| OSP | Orion Sampler audio sample (Synapse) |
| OSR | osu! osu! Replay |
| OSS | Office Saved Search (Microsoft Corporation) |
| OST | Exchange Server offline cache (Microsoft) |
| OST | On-Screen Takeoff project (On Center Software) |
| OST | Outlook offline cache (Microsoft) |
| OST | Tivoli Storage Manager data (IBM) |
| OSU | osu! Rhythm game beatmap |
| OSX | macOS program header (Apple) |
| OSZ | osu! Beatmap Package |
| OT | OpenTeacher Word list (OpenTeachers Maintainers) |
| OTA | OSKR firmware update (Digital Dream Labs) |
| OTA | Spartan Camera firmware (Frontier Pursuits) |
| OTA | X-plore alert tone (Lonely Cat Games) |
| OTA | Xbee 3 firmware update (Digi) |
| OTA | XnView over-the-air picture (XnSoft) |
| OTB | Nokia Phone Graphics Editor (Nokia) |
| OTB | On-the-air Bitmap |
| OTC | OpenOffice/StarOffice OpenDocument (Ver 2) Chart Template (Sun Microsystems, Inc.) |
| OTF | Blu-ray text subtitle font information file |
| OTF | FontForge OpenType font file |
| OTF | OnkoS text data file |
| OTF | OpenOffice/StarOffice OpenDocument formula template file (Sun Microsystems) |
| OTG | OpenOffice/StarOffice OpenDocument (Ver 2) Graphics Document Template (Sun Microsystems, Inc.) |
| OTH | OpenOffice/StarOffice OpenDocument (Ver 2) HTML Text Template (Sun Microsystems, Inc.) |
| OTH | Origin Graph Properties File (OriginLab Corporation) |
| OTH | Power Toys Other Folder Explorer Tool |
| OTHERFOLDER | Power Toys Other Folder Explorer Tool |
| OTI | OpenOffice/StarOffice OpenDocument (Ver 2) Image Template (Sun Microsystems, Inc.) |
| OTL | Fookes Super NoteTab Template File |
| OTL | NoteTab Outline |
| OTL | OpenTrap Event Log |
| OTL | Ventura Publisher's Type Foundry Outline Editor format |
| OTL | Z-Soft Type Foundry Font |
| OTM | Micro Cookbook data (IMSI) |
| OTM | Origin matrix template (OriginLab) |
| OTM | Outlook macro (Microsoft) |
| OTMM | Open Tibia Map Maker Tibia map data |
| OTN | OmniPage Training File (Nuance Communications, Inc.) |
| OTO | Autopano Project (Alexandre Jenny) |
| OTOSET | OTOsuite Settings (GN Otometrics) |
| OTP | OpenOffice/StarOffice OpenDocument (Ver 2) Presentation Template (Sun Microsystems, Inc.) |
| OTP | Origin Graphic Template File (OriginLab Corporation) |
| OTP | Top Secret Crypto Gold One Time Pad Key File (TAN$TAAFL Software Company) |
| OTRKEY | OnlineTvRecorder Encoded Video (OnlineTvRecorder.com) |
| OTS | OpenOffice/StarOffice OpenDocument (Ver 2) Spreadsheet Template (Sun Microsystems, Inc.) |
| OTS | OtsJuke Sound File |
| OTS | PSR-9000 (Yamaha Corporation of America) |
| OTT | Nokia Phone ringtone (Nokia) |
| OTT | Writer document template (Apache) |
| OTW | Origin Worksheet Template File (OriginLab Corporation) |
| OTX | Olivetti Olitext Plus File |
| OU! | OzWin CompuServe E-mail/Forum Access Outbound Messages Online |
| OUD | Adlib ExpressRecognition Server User Defined Dictionary (Adlib Software) |
| OUT | 3WayPack component file (The Three-Mode Company) |
| OUT | CompuServe E-mail |
| OUT | MyInfo documnet/outline file (Milenix Software) |
| OUT | NEi Nastran tabular output file (NEI Software) |
| OUT | NovaBACKUP backup set file (NovaStor) |
| OUT | Pro/ENGINEER temporary file (PTC) |
| OUT | PSpice output file (Cadence Design Systems) |
| OUT | PSS/E transmission file (Siemens) |
| OUT | TextPad output file (Helios Software Solutions) |
| OUT | Wireshark traffic log file |
| OUTPUT | Apple II operating system Golden Orchard Apple II CD Rom file |
| OUV | Sphinx Open Ended Responses (Le Sphinx Développement) |
| OUX | PCCharge File (VeriFone) |
| OV | OpenInsight Database Overflow File (Revelation Software) |
| OV | OrgPlus OrgViewer File (HumanConcepts, LLC) |
| OV1 | Program File - Overlay |
| OV2 | Program File - Overlay |
| OV2 | TomTom Point of Interest File (TomTom International BV) |
| OV3 | Program File - Overlay |
| OVA | Octava musical score file (Obtiv) |
| OVA | VirtualBox distribution software package file (Oracle) |
| OVA | Web Studio project page file (Beach Software) |
| OVA | Workstation distribution software package file (VMware) |
| OVB | OnkoS Vocabulary Backup File (OnkoS) |
| OVD | ObjectVision Datafile (Application) (Borland Software Corporation) |
| OVD | OverDisk Disk Use Database (Elias Fotinis) |
| OVE | Cakewalk Overture Score (Cakewalk) |
| OVERLAY | Streamlabs Desktop Streaming overlay configuration |
| OVF | VirtualBox open virtualization file (Oracle) |
| OVF | VMWare Workstation open virtualization file (VMware) |
| OVL | C++ Builder overlay (Embarcadero) |
| OVL | GPSBabel overlay (GPSBabel) |
| OVL | Jurassic World Evolution game data archive (Frontier Developments) |
| OVL | PDP-10 overlay (DEC) |
| OVL | RollerCoaster Tycoon game data archive (Frontier Developments) |
| OVLDEF | Gestionnaire d'extensions Overload Definition (Définition de surcharge) (Francis Gagné) |
| OVM | BHV Tonstudio Platin File |
| OVPN | AWS Client VPN Configuration file (Amazon) |
| OVPN | ExpressVPN Configuration file (Kape Technologies) |
| OVPN | Firewalla Configuration file (Firewalla) |
| OVPN | NordVPN Configuration file (Nord Security) |
| OVPN | OpenVPN Configuration file (OpenVPN) |
| OVPN | ProtonVPN Configuration file (Proton AG) |
| OVPN | VPN Gate Configuration file (National University of Tsukuba) |
| OVPN | VPNBook Configuration file (VPNBook) |
| OVPN | Windows Desktop Client Configuration file (Microsoft) |
| OVR | ArcGIS pyramid layers for raster datasets (ESRI) |
| OVR | Turbo Pascal overlay (Micro Focus) |
| OVS | ARTA Ovation 1 style sheet (ARTALABS) |
| OVW | Cool Edit Pro Overview File |
| OVW | Cubase .WAV File Image (Steinberg) |
| OVW | DIANA Overview File |
| OVX | Psion Oval Control (Psion PLC) |
| OW | Free Pascal Object File for Windows Version (FPC Development Team) |
| OWC | OutWit Hub OutWit Catch db Format (OutWit Technologies) |
| OWD | OpenWire Project |
| OWF | OnkoS Wave Data File (OnkoS) |
| OWG | OutWit Hub OutWit Gear db Format (OutWit Technologies) |
| OWL | C++ Builder script (Embarcadero) |
| OWL | Cloud Paks ontology/mappings (IBM) |
| OWL | Protégé biomedical data (NIGMS) |
| OWL | Sublime script (Sublime) |
| OWL | WebSphere transport classification data (IBM) |
| OWLE | OpenBuildings Designer building design project |
| OWM | OutWit Hub OutWit Mashup XML Format (OutWit Technologies) |
| OWS | Web Studio Project File (Back To The Beach Software, LLC) |
| OWX | WebProtégé Storing Ontologies |
| OX | Ox Object-Oriented Matrix Programming Language File |
| OXB | OlapX Report Portfolio (OlapX Software) |
| OXC | OlapX Cube Definition File (OlapX Software) |
| OXL | OMEGA Product Suite File |
| OXO | DB-MAIN Compiled Voyager-2 Program |
| OXO | Ox Object-Oriented Matrix Programming Language File |
| OXPS | XPS Viewer document (Microsoft) |
| OXPS | XPSView document (RootRise) |
| OXT | OpenOffice.org Extension (OpenOffice.org Community) |
| OXV | OlapX Local View File (OlapX Software) |
| OYB | Organize Your Beanie Babies Data File |
| OYZ | Lotus Approach Alternate dBASE Index |
| OZ | Job Management compressed backup data file (Opera Company) |
| OZD | OZ Document Embroidery Designs |
| OZF | Mozart Programming System Functor (Mozart Board) |
| OZF2 | OziExplorer Map (Des & Lorraine Newman) |
| OZFX3 | OziExplorer Image File (Des & Lorraine Newman) |
| OZIP | OPPO smartphones Firmware Updates |
| OZJ | MU Online Game Image File |
| OZM | Sharp Organizer Memo Bank |
| OZP | Sharp Organizer Telephone Bank |
| OZV | ORTIM Zeit Project (ORTIM Industrial Engineering Deutschland GmbH) |
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