| nrm | Lucene Norms File |
| nrmlib | Neat Cabinet File |
| nrrd | Nearly Raw Raster Data |
| nrx | Neat Receipt Folder File |
| ns | netCDF Data |
| ns | MongoDB Namespace File |
| ns1 | NetStumbler NS1 Log |
| ns2 | Lotus Notes 2 Database |
| ns3 | Lotus Notes 3 Database |
| ns4 | Lotus Notes 4 Database |
| nsa | AceBackup Archive File |
| nsb | AceBackup Backup File |
| nsbmd | Nintendo DS Model |
| nsbta | Nintendo DS Texture Animation |
| nscr | Nitro Screen Resource |
| nsd | BLAST Nucleotide Database |
| nsd | NRG Systems Symphonie Data |
| nsf | Lotus Notes Data |
| nsg | Nessie Saved State |
| nsi | BLAST NSI Data |
| nslloc | Mac OS X Finder NSL Location Data |
| nsm | NESticle Movie |
| nsmp | Nord User Sample |
| nsp | Nintendo Switch Submission Package |
| nspe | Navicat for SQL Server Exported Table |
| nsps | Navicat for SQL Server Structure Synchronization Data |
| nsq | BLAST Sequence Data |
| nsr | EMC NetWorker Directive File |
| nsx | Apollo HiPer-SIx Database Index |
| nt2 | NinjaTrader Level 2 Market Replay Data |
| nt3 | JB BAHN Layout Data |
| ntar | Network Trace And Retrieval Dump |
| ntb | Tecplot License Data |
| ntd | NinjaTrader Database |
| nte | Holonote Note |