| ob | ABF Outlook Backup Archive |
| 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 |
| oxt | OpenOffice.org Extension |
| ozip | oZip Compressed Data |
| ozip | Oppo Smartphone Firmware Update |
| p01 | Parity Archive V2 |
| p02 | Parity Archive V2 |
| p03 | Parity Archive V2 |
| p04 | Parity Archive V2 |
| p05 | Parity Archive V2 |
| p06 | Parity Archive V2 |
| p07 | Parity Archive V2 |
| p08 | Parity Archive V2 |
| p09 | Parity Archive V2 |
| p10 | Parity Archive V2 |
| p11 | Parity Archive V2 |
| p12 | Parity Archive V2 |
| pack | Pack200 Archive |
