| mz | MOZART Music Document |
| mzt | MOZART Score Template |
| n3 | Notation3 Document |
| nb | Mathematica Notebook File |
| nbk | SMART Notebook Document |
| nbml | Mathematica NotebookML File |
| ncd | Nero Cover Designer Document |
| ncd | NoteCase Pro Document |
| nce | NoteCase Pro Encrypted Document |
| nct | Nero Cover Designer Template |
| ncw | Nero Cover Designer Template |
| ncz | NoteCase Pro Compressed Document |
| nd | Intuit QuickBooks Network Data File |
| ndg | Network Notepad Network Diagram |
| ndo | Nendo Enhanced Native File |
| ndoc | Naver Word Document |
| ndw | Nemetschek Allplan Document |
| ne1 | OM2 OMALI NENA Encrypted Document |
| ne2 | OM2 OMALI NENA Encrypted Document |
| ne3 | OM2 OMALI NENA Encrypted Document |
| nec | NEC-JIS Encoded File |
| neu | Pro/ENGINEER Neutral Assembly |
| nff | WorldToolKit Neutral File Format Data |
| nfo | Microsoft System Information File |
| nfo | NFO File |
| nft | NetObjects Fusion Template |
| ng | Norton Guide |
| ngloss | Nisus Writer Pro Glossary |
| 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 |