| ndg | Network Notepad Network Diagram |
| ndo | Nendo Enhanced Native File |
| ndoc | Naver Word Document |
| ndtx | MyDraw XML Drawing Template |
| ndw | Nemetschek Allplan Document |
| ndx | MyDraw XML Drawing Document |
| ne1 | OM2 OMALI NENA Encrypted Document |
| ne2 | OM2 OMALI NENA Encrypted Document |
| ne3 | OM2 OMALI NENA Encrypted Document |
| ne4 | OM2 OMALI NENA Encrypted Document |
| nec | NEC-JIS Encoded File |
| neu | Pro/ENGINEER Neutral Assembly |
| nfd | Nefsis Document |
| nff | WorldToolKit Neutral File Format Data |
| nfo | Microsoft System Information File |
| NFO File |
| nft | NetObjects Fusion Template |
| ng | Norton Guide |
| ngdoc | AngularJS Document |
| ngloss | Nisus Writer Pro Glossary |
| nhb | Nero Burning ROM AVCHD-Video Compilation Data |
| nhf | Nero HFS CD Compilation |
| nhv | Nero HD-Burn Video Compilation |
| njx | NJStar Japanese WP Document |
| nlbl | NiceLabel Label |
| nld | Network Logic Diagram Document |
| nlx | FormWorx Form Document |
| nm5 | NovaMind 5 Mind Map Document |
| nmbtemplate | Numbers Spreadsheet Template |
| nmd | Nero MiniDVD Compilation |
| nmind | NovaMind 4 Mind Map Document |
| nms | Note-Mate Question Set |
| nmw | Netmeeting T126 Whiteboard Document |
| nof | NetObjects Fusion Document |
| not | E-Sword Notice |
| Veign Note-It Note |
| note | Notessimo Composition |
| Plain Text Document |
| notebook | SMART Notebook Document |
| notes | Plain Text Document |
| now | Plain Text Document |
| npd | Netrosoft Presentation Document |
| npp | Art Explosion Publisher Pro Document |
| nr3 | Nero MP3 CD Compilation |
| nr4 | Nero AAC CD Compilation |
| nra | Nero Audio CD Compilation |
| nrb | Nero Boot CD-Rom Compilation |
| nrc | Nero UDF/ISO CD-Rom Compilation |
| nrd | Nero DVD-Video Compilation |
| nre | Nero CD Extra Compilation |
| nrh | Nero Hybrid CD-Rom Compilation |
| nri | Nero ISO9660 CD-Rom Compilation |
| nrm | Nero Mixed Mode CD Compilation |
| nrs | Nero CD-Rom (EFI Boot) Compilation |
| nru | Nero UDF CD-Rom Compilation |
| nrv | Nero VideoCD Compilation |
| nrw | Nero WMA CD-Rom Compilation |
| nsd | Nero Super VideoCD Compilation |
| nsln | NiceLabel Solution |
| nsr | NewsRoom Document |
| nt7 | Orchida Knitting System Pattern |
| nta | Nota Aspel Document |
| nte | Asus EEE Note Document |
| ntg | New Tool Geometry File |
| ntp | MediaFACE CD Label |
| nts | Psion Organiser Notepad Document |
| ntt | MediaFACE Template |
| nud | Now Up-To-Date Calendar Document |
| num | Nashville Number System Chord |
| numbers | Numbers Spreadsheet File |
| numbers-tef | Apple Numbers iCloud Spreadsheet |
| nvc | Nero Vision Compilation |
| nvdl | NVDL Script |
| nwcp | Nisus Writer Pro Clipboard Document |
| nwd | NavisWorks JetStream Publisher Model |
| nwf | NavisWorks File |
| nws | Microsoft Internet News Message |
| nxl | Haansoft Nexcel Document |
| nxt | Haansoft Nexcel Template Document |
| nx__ | WriteNow 4 Document |
| nzb | Newzbin NZB Data |
| o2c | O2C 3D Model |
| o3m | Ortho 3D Model Document |
| oa2 | Fujitsu Oasys 2 Document |
| oa3 | Fujitsu Oasys 3 Document |
| oad | Notaro Document |
| oas | Fujitsu Oasys Document |
| obd | Microsoft Office Binder Document |
| obm | EIAS Camera Motion Export |
| obml | Opera Binary Markup Language Document |
| obo | OBO-Edit Document |
| obp | Bryce 3D Model |
| obt | Microsoft Office Binder Template |
| obx | OpenBook v8 Document |
| obz | Microsoft Office Binder Wizard |
| ocd | Orgadata LogiKal CAD Drawing |
| ocdc | Mathematica Document |
| ocf | GstarCAD Drawing |
| ocg | Osprey Custom Graph |
| ocr | FAXGrapper Fax Text |
