| nod | MSC Patran Nodal Results |
| nom | PC-DMIS NOM File |
| nop | Nikon Optional Picture Control |
| not | MakeMusic Finale Note File |
| not | Adobe InCopy User Dictionary |
| not | Zemax Element Drawing Note |
| notx | E-Sword v9 Study Note |
| notz | FiiNote Exported Note |
| nou | Numerical Electromagnetics Code Output |
| nov | Native Instruments Battery Data |
| np2 | Nikon Picture Control v2 Data |
| np3 | NP3 Compressed Nucleotide Database |
| npg | Magentic Data |
| npk | MikroTik Router OS Upgrade Package |
| npo | Nonpareil Redundancy Summary Output |
| nps | NTI Backup Now Partition Set |
| npw | nPassword Database File |
| npy | NumPy Data File |
| npz | NumPy Zipped Data |
| nqa | NQuery Advisor Data |
| nqi | ESET Smart Security Quarantined File Information |
| nrbak | NeatReceipts Backup Data |
| nrf | Lotus Notes Redirect File |
| nrf | Neat Document Folder File |
| nrm | Lucene Norms File |
| nrmlib | Neat Cabinet File |
| nrrd | Nearly Raw Raster Data |
| nrx | Neat Receipt Folder File |
| ns | MongoDB Namespace File |
| ns | netCDF Data |
