| nap | NAPLPS Metafile |
| nar | EMC NaviSphere Analyzer Archive |
| nas | Nastran Input File |
| natvis | Visual Studio Natvis Framework Data |
| nav | CART Navigator Data |
| nav | CART Grove Data |
| nav2 | WinAVI DVD Copy Temporary Data |
| navrep | Catia NavRep Data |
| nax | Moxy Portfolio Information Data |
| nb7 | NovaBACKUP v8 Backup Data |
| nbak | Neat Database Backup |
| nbd | NovaBACKUP Data File |
| nbe | Nessus Discovery Report |
| nbf | Windows Mobile Rom Upgrade File |
| nbfc | Nitro Basic File Character |
| nbfp | Nitro Basic File Palette |
| nbfs | Nitro Basic File Screen |
| nbh | HTC Hermes Rom Image |
| nbi | Nero BackItUp Information File |
| nbib | NCBI PubMed Export File |
| nbk | NovaBACKUP Job Definition File |
| nbkt | Native Instruments Battery Kits Data |
| nbm | NetBeans Module |
| nbo | nMod n-Body Model |
| nbr | NovaBench Report |
| nbt | Nero BackItUp Template |
| nbu | Nokia Phone Backup Archive |
| nbw | Notesbrowser Data |
| nc | Geopath NC File |
| nc1 | DSTV-CNC Data File |
| nc1 | NewsLeecher Cache |
| nc2 | NewsLeecher Cache |
| nc3 | netCDF Data |
| nc4 | netCDF Data |
| ncbr | Nitro Character Tile Data |