: O

.o
Compiled Object File N/A
.oab
Offline Address Book N/A
.oam
Adobe Edge Animate Widget File Adobe Systems
.oar
OpenSimulator Archive N/A
.ob!
Orbit Downloader Incomplete Download Orbit Downloader
.obb
Android Opaque Binary Blob File Google
.obd
Office Binder Document Microsoft
.obi
Outlook RSS Subscription File Microsoft
.obj
Wavefront 3D Object File Wavefront Technologies
.obml
Opera Mini Saved Web Page Opera Software
.obp
Bryce Object File DAZ Productions
.obt
Openbox Theme File Openbox
.obw
Superior Drummer Sounds File Toontrack
.obz
Compressed 3D Object File Smith Micro
.oc3
openCanvas 3 Event File Portalgraphics
.oc4
openCanvas 4 Event File Portalgraphics
.oc5
openCanvas 5 Event File Portalgraphics
.oca
Custom Control Library Type File Microsoft
.occ
Oceanic DataPool File Oceanic Consulting Corporation
.ocd
OCAD Map File OCAD
.oce
Open Catalog Extension Connection File Oracle
.oci
openCanvas Image Portalgraphics
.ocr
FAXGrapper Fax Text File Nuance Communications
.oct
Radiance Octree File Radiance
.octest
Xcode Objective-C Unit Test Bundle Apple
.ocx
ActiveX Control Microsoft
.od
Mascopt Graph Request File INRIA/UNSA
.odb
OpenDocument Database OASIS
.odc
Office Data Connection File Microsoft
.odf
OpenDocument Formula Oracle
.odg
OpenDocument Graphic File OASIS
.odi
OpenDocument Image OASIS
.odif
Open Document Interchange Format ITU-T
.odl
Object Description Language File Microsoft
.odm
OverDrive Media File OverDrive
.odo
Online Operating System Write Document iCUBE Network Solutions
.odp
OpenDocument Presentation Oracle
.ods
OpenDocument Spreadsheet Oracle
.odt
OpenDocument Text Document Oracle
.odx
BizTalk Server Orchestration File Microsoft
.oeaccount
Windows Mail Account File Microsoft
.oeb
Outlook Express Backup Wizard File QSX
.oem
OEM Setup File Microsoft
.oex
Opera Extension Opera Software
.ofc
Open Financial Connectivity File Microsoft
.off
Object File Format N/A
.ofl
Ots File List Ots Labs
.ofm
Melco Embroidery File Melco
.ofr
OptimFROG Audio File OptimFROG
.oft
Outlook File Template Microsoft
.ofx
Open Financial Exchange File N/A
.oga
Ogg Vorbis Audio File Xiph.Org
.ogf
S.T.A.L.K.E.R. Model File GSC Game World
.ogg
Ogg Vorbis Audio File Xiph.Org
.ogm
Ogg Media File N/A
.ognc
Dynamic Web Page N/A
.ogs
Origons Movie Data File Origons
.ogv
Ogg Video File Xiph.Org
.ogx
Ogg Vorbis Multiplexed Media File Xiph.Org
.ogz
Cube 2 Map File Wouter van Oortmerssen
.okt
Oktalyzer Module N/A
.ola
Online Access File N/A
.olb
OLE Object Library Microsoft
.old
Backup File N/A
.olk
Outlook Address Book File Microsoft
.olk14category
Outlook Category File Microsoft
.olk14contact
Outlook Contact File Microsoft
.olk14event
Outlook Calendar Event File Microsoft
.olk14group
Outlook Group File Microsoft
.olk14mailaccount
Outlook Mail Account File Microsoft
.olk14message
Outlook Message File Microsoft
.olk14msgsource
Outlook Email Message Data File Microsoft
.olk14note
Outlook Note File Microsoft
.olk14pref
Outlook Preferences File Microsoft
.olk14signature
Outlook Signature File Microsoft
.olk14task
Outlook Task File Microsoft
.olm
Mac Outlook Database File Microsoft
.olt
Orbit Downloads List Orbit Downloader
.oma
Sony OpenMG Music File Sony
.omcs
Office Manager Access File Krekeler
.omf
Open Media Framework File Avid Technology
.omg
OpenMG Audio File Sony
.omo
OMake Object File OMake
.omod
Oblivion Mod Archive N/A
.omp
Office Manager Document Archive Krekeler
.omx
OtsAV Media Library Information File Ots Labs
.ond
Lotus Notes Encapsulated Memo File IBM
.one
OneNote Document Microsoft
.onepkg
Microsoft OneNote Package File Microsoft
.onetoc2
Microsoft OneNote Table of Contents File Microsoft
.ont
theWord Bible Text Module theWord Bible Software
.ontx
theWord Encrypted Bible Text Module theWord Bible Software
.oo3
OmniOutliner 3 File The Omni Group
.ook
Arachne Batch Script Arachne
.opd
OmniPage Document Nuance Communications
.opdownload
Opera Partially Downloaded File Opera Software
.openbsd
OpenBSD Readme File N/A
.opf
Open Packaging Format File IDPF
.opj
OrCAD Project File Cadence Design Systems
.oplc
Nokia Operator Logo File Nokia
.opml
Outline Processor Markup Language File N/A
.ops
Office Profile Settings File Microsoft
.opt
Options File N/A
.options
SE-SOFT Configuration File SE-SOFT
.opts
Linux Configuration Options File N/A
.opus
Opus Audio File Xiph.Org
.opx
OrgPlus Org Chart Insperity Business Services
.oqy
Excel OLAP Query File Microsoft
.or2
Lotus Organizer 2 File IBM
.or3
IBM Lotus Organizer 97 File IBM
.or4
IBM Lotus Organizer 97 GS File IBM
.or5
Lotus Organizer 5 File IBM
.or6
Lotus Organizer 6 File IBM
.ora
Oracle Database Configuration File Oracle
.orc
Voyetra Digital Orchestrator File Voyetra
.orderedtest
Visual Studio Ordered Test File Microsoft
.ore
Ore Executable File crait
.orf
Olympus RAW File Olympus
.org
Lotus Organizer File N/A
.ori
Original File N/A
.orig
Original File N/A
.ort
Rich Text Editor Document IBM
.orv
Oracom Video File Oracom
.orx
RadiantOne VDS Database Schema Radiant Logic
.os
ObjectScript Source File ObjectScript
.osax
AppleScript Scripting Addition Apple
.osb
OpenStreetMap Binary Map File Merkaartor
.osc
OpenStreetMap Change File OpenStreetMap
.osdx
Search Connector Description File Microsoft
.osk
Osu! Skin File peppy
.osm
OpenStreetMap Map File OpenStreetMap
.osp
OpenShot Project File Jonathan Thomas
.osr
Osu! Replay File peppy
.oss
Microsoft Outlook Saved Search File Microsoft
.ost
Outlook Offline Folder File Microsoft
.osu
Osu! Script peppy
.osx
PowerPC Executable File N/A
.osz
Osu! Beatmap File peppy
.ot
theWord Old Testament Text Module theWord Bible Software
.ota
OTA Bitmap Image Nokia
.otb
Nokia Over The Air Bitmap Image Nokia
.otc
OpenDocument Chart Template OASIS
.otf
OpenType Font N/A
.otg
OpenDocument Graphic Template OASIS
.oth
OpenDocument HTML Template OASIS
.oti
OpenDocument Image Template OASIS
.otl
NoteTab Outline File Fookes Software
.otln
Opal Outline File A Sharp
.otm
Outlook Macro File Microsoft
.otp
OpenDocument Presentation Template OASIS
.otrkey
OnlineTvRecorder Encoded Video File OnlineTvRecorder.com
.ots
OpenDocument Spreadsheet Template OASIS
.ott
OpenDocument Document Template OASIS
.otx
theWord Encrypted Old Testament Text Module theWord Bible Software
.otz
OpenLP Theme File OpenLP
.out
Output File N/A
.ov2
TomTom Points of Interest Database TomTom
.ova
Open Virtual Appliance VMware
.ove
Overture Musical Score GenieSoft
.ovf
Open Virtualization File VMware
.ovl
Rollercoaster Tycoon 3 Data File Atari
.ovp
The Overlay Maker Package File The Overlay Maker
.ovpn
OpenVPN Configuration File OpenVPN Technologies
.ovr
The Overlay Maker Overlay File The Overlay Maker
.ovw
Logic Pro Overview File Apple
.ow
Free Pascal 1.0.x Object File Free Pascal
.owc
OutWit Catch Database OutWit Technologies
.owg
OutWit Gear Database OutWit Technologies
.owl
OWL Source Code File N/A
.owm
OutWit XML Mashup File OutWit Technologies
.oxps
OpenXPS File Microsoft
.oxt
Apache OpenOffice Extension Sun Microsystems
.oxygene
Oxygene Project File RemObjects
.oyx
Approach Alternate Database Index N/A
.oz
Opera Job Management Compressed File Opera Company