| nca | Switch Nintendo Content Archive |
| nfp | Nokia Flash Package |
| nhn | ijji REACTOR Game Package |
| npf | NTI Backup Now Partition File |
| nsk | NaShrinK Compressed Archive |
| nuget | NuGet Package |
| nvz | Novelty Content Package |
| nxa | NanoTrader Nano Export Archive |
| nz | NanoZip Compressed Archive |
| oap | Bada Signed Installation Package |
| oar | OpenSimulator Archive |
| ob | ABF Outlook Backup Archive |
| ob5 | TopLang OE Backup Data |
| obb | Android Opaque Binary Blob File |
| obml15 | Opera Mini Saved Web Page |
| obml16 | Opera Mini Saved Web Page |
| oex | Opera Extension |
| ofb | Oxygen Forensic Suite Backup |
| ogp | OpenG Package |
| olp | Microsoft Office Live Package |
| omp | Office Manager Document Archive |
| oop | OOP Compressed Archive |
| opg | OpenG Package File |
| opk | Origin Pack File |
| opx | Origin v8 Package File |
| ova | Open Virtual Appliance |
| owr | PeopleSoft Enterprise Results Archive |
| oxt | OpenOffice.org Extension |
| ozip | oZip Compressed Data |
| ozip | Oppo Smartphone Firmware Update |
