| hto | Survex Hierarchical Tagged Objects File |
| htpasswd | Apache Password File |
| htri | HTRI Xchanger Suite Data Input file |
| hts | HyperTuner Skin |
| htv | HTV Teletekst Data |
| htw | Webhits Template |
| hub | Lattice Reveal Analyzer HUB Data |
| hud | HUD Maker File |
| huf | DtSearch Huffman Compression Table |
| huh | HydroCAD Unit Hydrograph Definitions |
| hun | Personal Paint Hungarian Language Data |
| hv | Microsoft Windows Mobile Hive |
| hvc | HotDocs Variable Collection File |
| hvd | Yamaha HV Voice Dictionary Data |
| hve | Microsoft Windows 8 AMCache Registry Hive |
| hvi | M3601A HVI Data |
| hvif | Haiku Vector Icon Format Data |
| hvs | Yamaha HV-Script |
| hvz | HoloViews Exported Data |
| hvz | hyperVIEW Simulation Data |
| hw | Marvelous Designer Hardware ID Data |
| hwdb | Linux Hardware Database |
| hwe | PLINK Hardy-Weinberg Exact Test Statistic Report |
| hwf | Hantek HDG2000B Wave Format Data |
| hwl | BrailleNote Apex License Key File |
| hwrx | Microvellum Hardware File |
| hwt | Huawei Phone Theme |
| hwv | Hades Waveform Viewer Data |
| hwx | RSNetWorx Registration Data |
| hxb | QCTest Data |
| hxd | Microsoft Help 2 Validator Data |
| hxg | Microsoft Help 2 Filter Cache |
| hxh | Microsoft Help 2 Merged TOC |
| hxi | Microsoft Help 2 Compiled Help Index |
| hxq | Microsoft Help 2 Query Data |