| File extension | Developer/Producer | File description |
|---|---|---|
| O file extension | N/A | Object Format |
| O01 file extension | FMJ-Software | Typhoon Voice |
| O2C file extension | N/A | Objects To See 3D |
| O8D file extension | N/A | OCTGN Deck |
| O8G file extension | N/A | OCTGN Game Definition |
| O8O file extension | N/A | Mediator 5 Repository Tabs Vorlagen.006 |
| O8S file extension | N/A | OCTGN Set |
| OAB file extension | N/A | Microsoft Outlook Offline Address Book Format |
| OAD file extension | OA SISTEMI | Suite Notaro Document |
| OAF file extension | Microsoft Studios | Microsoft Flight Simulator Texture |
| OAM file extension | Adobe Systems | Adobe Edge Overlay Format |
| OAP file extension | Samsung Group | Samsung Bada Signed Installation Package |
| OAR file extension | N/A | OpenSimulator Archive Format |
| OAS file extension | rsbr Software | Microsoft Outlook Attachment Sniffer |
| OAT file extension | Google Inc. | Google Android RunTime Code |
| OAV file extension | Microsoft Studios | Microsoft Flight Simulator Texture |
| OAW file extension | N/A | OpenArchitectureWare Workflow |
| OAZ file extension | N/A | NetFax Manager OAZ Fax Image |
| OB file extension | IBM | IBM LinkWay Object |
| OB! file extension | OrbitDownloader.com | Orbit Downloader Incomplete Download Format |
| OB3 file extension | ABF software, Inc. | ABF Software Outlook Backup Backup |
| OB5 file extension | N/A | TopLang OE Backup |
| OBAK file extension | SYNAMETIRCS | WinSQL Offline Backup |
| OBB file extension | Google Android Opaque Binary Blob Format | |
| OBD file extension | Microsoft | Microsoft Office Binder Document Format |
| OBF file extension | OsmAnd Development Project | OsmAnd Offline GPS Vector Maps |
| OBG file extension | Pixologic, Inc. | ZBrush Mesh |
| OBI file extension | Microsoft | Microsoft Outlook 2007/2010/2013 RSS Subscription Format |
| OBJ file extension | N/A | 3D Object Format |
| OBJX file extension | DAZ 3D Inc. | Metatools Object Bryce Support |
| OBK file extension | Cadence Design Systems, Inc. | OrCAD Capture Design Or Library |
| OBL file extension | Caligari Corporation | TrueSpace |
| OBML file extension | Opera Software | Opera Mini Saved Web Page Format |
| OBML15 file extension | Opera Software ASA | Opera Mini 5.1 Saved Web Page |
| OBP file extension | DAZ Productions | Bryce Object Format |
| OBPACK file extension | Stardock Corporation | ObjectBar Theme Pack |
| OBR file extension | Micro Focus International plc | Borland C++ Object Browser Data |
| OBS file extension | N/A | ObjectScript Script Format |
| OBT file extension | Openbox | Openbox Theme Format |
| OBV file extension | Mootools software | 3D Photo Browser Thumbnail Cache |
| OBW file extension | Toontrack | Toontrack Superior Drummer Audio Format |
| OBX file extension | IBM | Rational XDE |
| OBYX file extension | Obyx | Obyx Control |
| OBZ file extension | Smith Micro | Compressed 3D Object Format |
| OC3 file extension | Portalgraphics | OpenCanvas 3 Event Format |
| OC4 file extension | Portalgraphics | OpenCanvas 4 Event Format |
| OC5 file extension | Portalgraphics | OpenCanvas 5 Event Format |
| OC9 file extension | EcoMerc | OrgCon Organization |
| OCA file extension | Microsoft | Custom Control Library Type Format |
| OCAMLMAKEFILE file extension | N/A | Caml Programming Language Makefile |
| OCB file extension | OriginLab Corporation | Origin Precompiled Origin C |
| OCC file extension | Oceanic Consulting Corporation | Oceanic DataPool Format |
| OCD file extension | OCAD | OCAD Digitized Map Format |
| OCDC file extension | Wolfram Research, Inc. | Mathematica Document |
| OCDF file extension | Recorded Books LLC | OneClickDigital Mp3 Audio Book |
| OCE file extension | Oracle | Open Catalog Extension Connection Format |
| OCEN file extension | N/A | EdGCM Data |
| OCF file extension | OM2 Technology Inc. | OM2 Cipher |
| OCG file extension | Mount Sinai Hospital | Osprey Custom Graph |
| OCI file extension | Portalgraphics | OpenCanvas Image Format |
| OCM file extension | AOL Inc. | Netscape Communicator Aim |
| OCP file extension | N/A | Advanced Art Studio Image |
| OCR file extension | Nuance Communications | FaxGrapper FAX Transcribed Text Format |
| OCT file extension | Radiance | RADIANCE Octree Format |
| OCTEST file extension | Apple | Xcode Objective-C Unit Test Bundle |
| OCV file extension | N/A | OCV Training Data |
| OCX file extension | Microsoft | ActiveX Control Format |
| OC_ file extension | N/A | Compressed ActiveX Control |
| OD file extension | INRIA/UNSA | Mascotte Mascopt Request Format |
| OD1 file extension | TigerLogic Corp. (Omnis Technology Corporation) | Omnis 5 Database |
| OD2 file extension | TigerLogic Corp. (Omnis Technology Corporation) | Omnis 5 Database |
| OD3 file extension | TigerLogic Corp. (Omnis Technology Corporation) | Omnis Studio Database |
| OD4-9 file extension | N/A | Omnis5 Database |
| ODB file extension | OASIS | OpenOffice.org OpenDocument Database Format |
| ODC file extension | Microsoft | Microsoft Office Database Connection Format |
| ODCCUBEFILE file extension | N/A | OpenDocument 1 |
| ODCNEWFILE file extension | Microsoft Corporation | Microsoft Office Data Connection |
| ODCTABLEFILE file extension | Microsoft Corporation | Microsoft Office |
| ODE file extension | Microsoft Corporation | Microsoft Office |
| ODEX file extension | Google Inc. | Google Android Optimized Executalbe |
| ODF file extension | Sun Microsystems | Open Document Interchange Format (ODIF) |
| ODG file extension | OASIS | OpenDocument Drawing Format |
| ODH file extension | Microsoft Corporation | Microsoft Visual Studio Interface Definition Language |
| ODI file extension | OASIS | OpenOffice.org Image Format |
| ODIF file extension | ITU-T | Open Document Interchange Format |
| ODL file extension | Microsoft | Object Description Language Format |
| ODM file extension | Sun Microsystems | OpenOffice.org OpenDocument Global Text Document Format |
| ODO file extension | iCUBE Network Solutions | ICUBE Online Operating System Write Document Format |
| ODP file extension | Sun Microsystems | OpenOffice.org OpenDocument Presentation Format |
| ODS file extension | Sun Microsystems | OpenDocument Spreadsheet Format |
| ODT file extension | Sun Microsystems | ODF Text Document Format |
| ODT# file extension | OpenOffice.org Project Team | OpenOffice.org Locked Document |
| ODTPC file extension | Oracle Corporation | Oracle User Productivity Kit Presentation |
| ODTTF file extension | Microsoft Corporation | Microsoft Office Document Embedded Font |
| ODV file extension | N/A | Ocean Data View Data |
| ODVI file extension | N/A | LaTeX |
| ODX file extension | Microsoft | Microsoft BizTalk Server Diagram Format |
| OD_ file extension | Oracle Corporation | Oracle Compressed Driver |
| OEACCAOUNT file extension | Microsoft Corporation | Windows Mail |
| OEACCOUNT file extension | Microsoft | Windows Mail Account Settings Format |
| OEB file extension | QSX | Outlook Express Backup Wizard Format |
| OECL file extension | N/A | Open EDA Component Library |
| OEF file extension | IBM | Optim Export |
| OEM file extension | Microsoft | OEM Install Data Format |
| OEMIGACCOUNT file extension | Microsoft Corporation | Outlook Express Temporary |
| OET file extension | eSignal | ESignal Order Entry Ticket |
| OEX file extension | Opera Software | Opera Add-on Format |
| OFA file extension | Eastman Kodak Company | Kodak OfotoNow |
| OFB file extension | Oxygen Software Company | Oxygen Forensic Suite Backup |
| OFC file extension | Microsoft | Open Financial Connectivity Format |
| OFD file extension | Cypresslogic Systems Inc. | ObjectView Form Definition |
| OFF file extension | N/A | DEC 3D Object File Format |
| OFFICEUI file extension | Microsoft Corporation | Microsoft Office UI Customization |
| OFFSETS file extension | N/A | Offset |
| OFL file extension | Ots Labs | OtsTurntables Playlist |
| OFM file extension | Nuance Communications | OmniForm Form Format |
| OFN file extension | Microsoft Corporation | MS Office File New (Other Office Documents) |
| OFP file extension | Objecteering Software | Objecteering Project |
| OFR file extension | OptimFROG | OptimFROG Encoded Audio |
| OFS file extension | N/A | OptimFROG Dualstream |
| OFT file extension | Microsoft | Microsoft Outlook Template Format |
| OFX file extension | N/A | Open Financial Exchange Format |
| OGA file extension | Xiph.Org | Ogg Vorbis Audio Profile Format |
| OGD file extension | Oracle Corporation | Oracle Forms Graph |
| OGF file extension | GSC Game World | S.T.A.L.K.E.R. Model Format |
| OGG file extension | Xiph.Org | Ogg Vorbis Audio Format |
| OGL file extension | N/A | ATI Overlay Source Code |
| OGM file extension | Xiph.Org | Ogg Vorbis Media Format |
| OGNC file extension | N/A | Dynamic Web Page Format |
| OGO file extension | N/A | Origin Graphic Object |
| OGR file extension | N/A | OGR C++ Open Source Library |
| OGS file extension | Origons | Origin Script Format |
| OGV file extension | Xiph.Org | Ogg Vorbis Video Format |
| OGW file extension | OriginLab Corporation | OriginLab Worksheet |
| OGX file extension | Xiph.Org | Ogg Vorbis Multiplex Profile |
| OGZ file extension | Wouter van Oortmerssen | Cube 2 Sauerbraten Map Format |
| OH file extension | N/A | DrillAssistant List |
| OH4 file extension | Efka-Soft | Overhoor List |
| OHP file extension | Microsoft Corporation | MS-DOS 7 |
| OHS file extension | RAD Game Tools, Inc. | Bink Outbound History |
| OHW file extension | N/A | Overhoor DrillAssistant List |
| OIF file extension | Intuit Inc. | QuickBase Web-sharable Database Interchange |
| OIL file extension | N/A | Open Image Library Format Image Format |
| OJP file extension | N/A | 3WayPack |
| OK file extension | Robelle | QEDIT |
| OKM file extension | Gian Paolo Saliola | OkMap Map Defining |
| OKOZO file extension | Okozo | Okozo Desktop Animation |
| OKR file extension | CyberLink Corp. | PowerRecover One Key Recovery |
| OKS file extension | Mike Mardesich | OKScript |
| OKT file extension | N/A | Oktalyzer Music Module (MOD) Format |
| OKX file extension | Mike Mardesich | OKScript |
| OL file extension | Valve Corporation | Valve Hammer Object Layout |
| OLA file extension | N/A | Online Access Format |
| OLB file extension | Microsoft | Microsoft Office OLE Object Library Format |
| OLB2 file extension | Abbot Systems | CanOpener Library |
| OLD file extension | N/A | Backup Format |
| OLE file extension | Microsoft Corporation | Microsoft Object Linking And Embedding |
| OLE2 file extension | Microsoft Corporation | Microsoft Office Binary Document Container Format |
| OLF file extension | Oyez Legal Software | OyezForms Legal Documents |
| OLK file extension | Microsoft | Microsoft Outlook Address Book Format |
| OLK14CATEGORY file extension | Microsoft | Microsoft Outlook 2011 For Mac Category Format |
| OLK14CONTACT file extension | Microsoft | Microsoft Outlook 2011 For Mac Contact Format |
| OLK14DBHEADER file extension | Microsoft Corporation | Microsoft Outlook 2011 For Mac Database |
| OLK14EVENT file extension | Microsoft | Outlook Calendar Event Format |
| OLK14FOLDER file extension | Microsoft Corporation | Microsoft Outlook 2011 For Mac Folder |
| OLK14GROUP file extension | Microsoft | Outlook Group Format |
| OLK14MAILACCOUNT file extension | Microsoft | Microsoft Outlook 2011 For Mac Mail Account Settings Format |
| OLK14MESSAGE file extension | Microsoft | Microsoft Outlook 2011 For Mac Message Format |
| OLK14MSGATTACH file extension | Microsoft Corporation | Microsoft Outlook 2011 For Mac Message Attachment |
| OLK14MSGSOURCE file extension | Microsoft | Microsoft Outlook 2011 For Mac Message Source Format |
| OLK14NOTE file extension | Microsoft | Outlook Note Format |
| OLK14PREF file extension | Microsoft | Microsoft Outlook 2011 For Mac Preferences Format |
| OLK14RECENT file extension | Microsoft Corporation | Microsoft Outlook 2011 For Mac Recent Address |
| OLK14RULE file extension | Microsoft Corporation | Microsoft Outlook 2011 For Mac Rule |
| OLK14SCHEDULE file extension | Microsoft Corporation | Microsoft Outlook 2011 For Mac Schedule |
| OLK14SEARCH file extension | Microsoft Corporation | Microsoft Outlook 2011 For Mac Saved Search |
| OLK14SIGNATURE file extension | Microsoft | Microsoft Outlook 2011 For Mac Signature Format |
| OLK14TASK file extension | Microsoft | Outlook Task Format |
| OLK14UID file extension | Microsoft Corporation | Microsoft Outlook 2011 For Mac UID |
| OLL file extension | inData Corporation | TrialDirector Load |
| OLM file extension | Microsoft | Microsoft Outlook For Mac Data Format |
| OLN file extension | Microsoft Corporation | Microsoft Visual C++ Outline Examples |
| OLPROJ file extension | Adobe Systems Incorporated | Adobe OnLocation |
| OLS file extension | Microsoft Corporation | Microsoft Office List Shortcut |
| OLT file extension | Orbit Downloader | Orbit Downloader Download List Format |
| OLV file extension | Chris Sawyer | Roller Coaster Tycoon |
| OLY file extension | IBM | AFP Advanced Function Presentation Overlay Resource |
| OMA file extension | Sony | Sony OpenMG Music Format |
| OMC file extension | OriginLab Corporation | Origin Customized Menu |
| OMCS file extension | Krekeler | Office Manager Access Format |
| OMD file extension | Pitney Bowes Software Inc. (MapInfo) | MapInfo Routing J Server Data |
| OMEG file extension | Wolfram Research, Inc. | Mathematica For Mac |
| OMF file extension | Avid Technology | Open Media Framework Format |
| OMFI file extension | N/A | Open Media Framework |
| OMG file extension | Sony | OpenMG Jukebox Audio Format |
| OML file extension | Lambda Research Corporation | TracePro Model |
| OMN file extension | N/A | Omnipotent Collection |
| OMO file extension | OMake | OMake Object Format |
| OMOD file extension | N/A | Oblivion Mod Manager Mod Format |
| OMP file extension | Krekeler | Office Manager Pro Document Archive |
| OMR file extension | Abhinav Parihar | OMR Template |
| OMS file extension | Briggs Softworks | Order Maven |
| OMT file extension | Open Channel Software | SITH HLA Object Model Template |
| OMX file extension | Ots Labs | OtsAV Media Library Information Format |
| ON2 file extension | N/A | On2 Encoded FLV |
| OND file extension | IBM | Lotus Notes Format |
| ONE file extension | Microsoft | Microsoft OneNote Document Format |
| ONECACHE file extension | Microsoft Corporation | Microsoft OneNote Cache |
| ONEPKG file extension | Microsoft | Microsoft OneNote Package Format |
| ONETMP file extension | Microsoft Corporation | Microsoft OneNote Temporary |
| ONETOC file extension | Microsoft Corporation | Microsoft OneNote Table Of Contents |
| ONETOC2 file extension | Microsoft | Microsoft OneNote Table Of Contents Format |
| ONM file extension | Maptech, Inc. | Outdoor Navigator Map |
| ONT file extension | theWord Bible Software | TheWord Module Format |
| ONTX file extension | theWord Bible Software | TheWord Encrypted Module Format |
| ONW file extension | Omron Corporation | Omron HMI NTST |
| ONX file extension | Onyx Computing, Inc. | OnyxGrass Image |
| OO3 file extension | N/A | Omni Group Outliner 3 Format |
| OOG file extension | Python Software Foundation | PyGraph Python Graphics Interface Object Oriented Graphics |
| OOGL file extension | Geometry Center at the University of Minnesota | Geomview Object Oriented Graphics Library |
| OOK file extension | Arachne | Arachne Batch Script Format |
| OOS file extension | OpenOffice.org Project Team | OpenOffice.org Spreadsheet |
| OOT file extension | OpenOffice.org Project Team | OpenOffice.org Text |
| OP file extension | eSignal | ESignal OptionsPlus |
| OP2 file extension | Dynamix, Inc. | Outpost 2 Saved Game |
| OP4 file extension | MSC Software Corporation | Nastran Output |
| OPA file extension | Terminal Reality | Fly! RAW Image Opacity Map |
| OPAL file extension | Microsoft Corporation | Microsoft Office Customization Tool (OCT) Language-specific Settings |
| OPAX file extension | Microsoft Corporation | Microsoft Office Customization Tool (OCT) Standard Settings |
| OPB file extension | DAZ 3D Inc. | Bryce Object |
| OPC file extension | Microsoft Corporation | Microsoft Office 97 Upgrade Control |
| OPD file extension | Nuance Communications | OmniPage Document Format |
| OPDOWNLOAD file extension | Opera Software | Opera Next Incomplete Download |
| OPEF file extension | Softex Incorporated | OmniPass Encrypted Folder |
| OPF file extension | IDPF | Open Packaging Format |
| OPG file extension | N/A | Offline Plan Generation Package |
| OPI file extension | Adlib Software | Adlib OCR Processing Information |
| OPJ file extension | Cadence Design Systems | OrCAD Capture Project Format |
| OPK file extension | N/A | Sinking Island/LIle Noyée Game |
| OPLC file extension | Nokia | Nokia Logo Format |
| OPLM file extension | N/A | Outline Processor Markup Language |
| OPML file extension | N/A | OPML Outline Processor Markup Language File Format |
| OPN file extension | N/A | Court Opinion |
| OPP file extension | Kerensoft | IPhotoDVD |
| OPPC file extension | Relic Entertainment Inc. | Space Marine Game Resource Package |
| OPQ file extension | Basilisk Games | Eschalon: Book I Game |
| OPR file extension | OPRO Japan Co.,Ltd. | OPRO X Browser |
| OPS file extension | N/A | Microsoft Office Profile Settings Format |
| OPT file extension | N/A | Options Format |
| OPTIONS file extension | SE-SOFT | SE-SOFT Configuration Format |
| OPTS file extension | N/A | Linux Configuration Options Format |
| OPUS file extension | Xiph.Org | Opus Audio Format |
| OPW file extension | Insperity, Inc. | OrgPlus For Windows Organization Chart |
| OPX file extension | HumanConcepts | Microsoft Office Organization Chart File Format |
| OPXT file extension | Insperity, Inc. | OrpPlus Template |
| OPY file extension | OptiY GmbH | OptiY Model |
| OP_ file extension | GkWare e.K. | GKSetup Support |
| OQY file extension | Microsoft | Microsoft Excel OLAP Query Format |
| OR2 file extension | IBM | Lotus Organizer 2 Format |
| OR3 file extension | IBM | IBM Lotus Organizer 97 Format |
| OR4 file extension | IBM | Lotus Organizer Data Format |
| OR5 file extension | IBM | IBM Lotus Organizer Format |
| OR6 file extension | IBM | Lotus Organizer Data Format |
| OR8 file extension | IBM | Rational Rose Oracle8 Database Model Report |
| ORA file extension | Oracle | Oracle Database Parameter Configuration Format |
| ORB file extension | N/A | Original EBook Reader Ebook |
| ORC file extension | Voyetra | CSound Orchestra Midi Format |
| ORDEREDTEST file extension | Microsoft | Microsoft Visual Studio Ordered Test Format |
| ORE file extension | crait | Ore Executable Format |
| ORF file extension | Olympus | Olympus Digital Camera Raw Image Format |
| ORG file extension | N/A | Lotus Organiser Format |
| ORG2+ file extension | IBM | Lotus Organizer |
| ORIG file extension | N/A | Original Format |
| ORIGINAL file extension | NetObjects Inc. | Netobjects Fusion Components Bbscomp Message |
| ORIGINAL_EPUB file extension | N/A | EPUB Ebook Backup |
| ORIGINAL_MOBI file extension | N/A | MOBI Ebook Backup |
| ORK file extension | Games Workshop Group PLC | Warhammer Mark Of Chaos Game Archive |
| ORL file extension | N/A | Object-Relational Language |
| ORMDESIGNER file extension | Inventic s.r.o. | ORM Designer Project |
| ORS file extension | N/A | DSP Group TrueSpeech Audio Format |
| ORT file extension | IBM | Rich Text Editor Document |
| ORV file extension | Oracom | Oracom Video Format |
| ORX file extension | Radiant Logic | RadiantOne Virtual Directory Server Database Schema |
| ORZ file extension | Netgame | Holic Game |
| OS file extension | ObjectScript | ObjectScript Source Format |
| OS2 file extension | IBM | Os2 System |
| OS3 file extension | IBM | OS/2 Warp 3 |
| OSA file extension | N/A | W32/Sober-AD |
| OSAS file extension | N/A | Apple Script Library Tani Script |
| OSAX file extension | Apple | AppleScript Scripting Addition |
| OSB file extension | Merkaartor | OpenStreetMap Binary Map Format |
| OSBX file extension | Lunabee Pte Ltd | OneSafe Exported Backup |
| OSC file extension | OpenStreetMap | OptionScope Worksheet Format |
| OSCD file extension | hexler | TouchOSC Interface Editor Template |
| OSD file extension | Microsoft Corporation | Open Software Description |
| OSDX file extension | Microsoft | Microsoft Windows Search Connector Format |
| OSF file extension | Interplay Entertainment Corporation | Descent 3 Sound |
| OSG file extension | osg.js | OSGJS JSON Input |
| OSK file extension | peppy | Osu! Skin Format |
| OSL file extension | Ockam Instruments, Inc. | OckamSoft Log |
| OSM file extension | OpenStreetMap | OpenStreetMap Data Format |
| OSP file extension | Jonathan Thomas | OpenShot Project Format |
| OSR file extension | peppy | Osu! Game Replay Format |
| OSS file extension | Microsoft | Microsoft Office Saved Search Format |
| OST file extension | Microsoft | Microsoft Outlook Inbox Off-line Folder Format |
| OSU file extension | peppy | Osu! Dialog Format |
| OSW file extension | Keisokugiken corporation | ONESWING Contents |
| OSX file extension | N/A | Apple Mac OS PowerPC Executable Format |
| OSZ file extension | peppy | Osu! Beatmap Format |
| OT file extension | theWord Bible Software | TheWord Text Module Format |
| OTA file extension | Nokia | OTA Bitmap Format |
| OTB file extension | Nokia | Nokia OTA Bitmap Format |
| OTC file extension | OASIS | OpenDocument Chart Template Format |
| OTD file extension | N/A | OpenIV Texture Data |
| OTF file extension | N/A | OpenType Font File Format |
| OTG file extension | OASIS | OpenOffice.org Graphics Document Template |
| OTH file extension | N/A | OpenOffice.org OpenDocument HTML Text Template |
| OTI file extension | OASIS | OpenDocument Image Template Format |
| OTL file extension | Fookes Software | Super NoteTab Template Format |
| OTLN file extension | A Sharp | Opal Outline Format |
| OTM file extension | Microsoft | Microsoft Outlook Macro Format |
| OTP file extension | N/A | OpenOffice.org Presentation Template Format |
| OTR file extension | Silicon Graphics, Inc. | IRIX Complied FTR |
| OTRKEY file extension | OnlineTvRecorder.com | OTRKEY Encoded Video Format |
| OTS file extension | N/A | OpenOffice.org OpenDocument Spreadsheet Template Format |
| OTT file extension | N/A | OpenOffice.org Text Document Template Format |
| OTV file extension | QIAGEN | Rotor-Disc OTV Kit OTV Calibration |
| OTX file extension | theWord Bible Software | TheWord Encrypted Module Format |
| OTZ file extension | OpenLP | OpenLP Theme Format |
| OUT file extension | N/A | Output Format |
| OUTLINE file extension | Neuber Software | FontTwister Letter Outline |
| OUTLOOK97 file extension | Microsoft Corporation | Microsoft Outlook Custom Mail |
| OUX file extension | Olle Persson | Bibexcel |
| OV file extension | Revelation Software | OpenInsight Database Overflow |
| OV1 file extension | Microsoft Corporation | Overlay |
| OV2 file extension | TomTom | TomTom Navigator Point Of Interest Format |
| OV3 file extension | Microsoft Corporation | Overlay |
| OV4 file extension | Microsoft Corporation | Overlay |
| OV5 file extension | Microsoft Corporation | Overlay |
| OVA file extension | Obtiv | Open Virtual Machine Format |
| OVD file extension | Borland Software Corporation | ObjectVision Data |
| OVE file extension | GenieSoft | Overture Music Score Format |
| OVF file extension | VMware | Open Virtualization Format Package |
| OVG file extension | Borland Software Corporation | ObjectVision Converted Graphic |
| OVH file extension | Marcel Kuhnt und Rüdiger Hülsmann | OMSI Bus Settings |
| OVL file extension | Atari | RollerCoaster Tycoon 3 Sprite Format |
| OVOLOG file extension | ooVoo LLC | OoVoo Log |
| OVP file extension | The Overlay Maker | The Overlay Maker Package Format |
| OVPN file extension | OpenVPN Technologies | OpenVPN Config Format |
| OVR file extension | The Overlay Maker | Overlay Format |
| OVS file extension | David Pilling | Ovation 1 Style Sheet |
| OVW file extension | Apple | Logic Pro Overview Format |
| OW file extension | Free Pascal | Free Pascal For Windows Object Format |
| OWC file extension | OutWit Technologies | OutWit Hub OutWit Catch Db Format |
| OWG file extension | OutWit Technologies | OutWit Hub OutWit Gear Outwit Thesaurus Db Format |
| OWL file extension | N/A | OWL (Obfuscated Weird Language) Source Code Format |
| OWM file extension | OutWit Technologies | OutWit Hub OutWit Mashup XML Format |
| OWR file extension | Oracle Corporation | PeopleSoft Results Archive |
| OWS file extension | Beach Software, LLC | Web Studio Project |
| OWT file extension | Ancestry.com Inc. | Ancestry.com OneWorldTree |
| OX file extension | Jurgen A Doornik | Ox Object-oriented Matrix Programming Language |
| OXD file extension | N/A | PS3 Proxy Server |
| OXF file extension | N/A | IBM Rational Rhapsody |
| OXO file extension | Jurgen A Doornik | Ox Object-Oriented Matrix Programming Language |
| OXPS file extension | Microsoft | Windows 8 OpenXPS Document Format |
| OXT file extension | Sun Microsystems | OpenOffice.org Extension Help Format |
| OXYGENE file extension | RemObjects | Oxygene Project Format |
| OYX file extension | N/A | IBM Lotus Approach Alternate Database Index Format |
| OYZ file extension | dataBased Intelligence, Inc. | Lotus Approach Alternate DBASE Index |
| OZ file extension | Opera Company | Opera Job Management Compressed Format |
| OZF2 file extension | Des & Lorraine Newman | OziExplorer Map |
| OZFX3 file extension | Des & Lorraine Newman | OziExplorer Image |
| OZJ file extension | Webzen | Mu Online Graphic |
| OZP file extension | Orgadata AG | Orgadata LogiKal |
| OZT file extension | Webzen | Mu Online Texture |
Web Developer acting on his own, author of Internet solutions facilitating working with new technologies for less advanced users. Internet maniac.
