| hsm | AQUA Hydrogen Bond Distance Restraints Summary Data |
| hsn | HostScan Hosts Data |
| hsp | iGO Primo Histspeed File |
| hsr | RezeptAssist Exported Data |
| hss | Adobe Photoshop Hue/Saturation Data |
| hst | General History File |
| hstx | Altair HyperStudy Package |
| hsw | STEPS Frequency Response Data |
| ht1 | Google Desktop HT1 File |
| hta | S10 WebAlbums Data |
| htb | Audacity Help File |
| hte | HealthStream Express Exported Test Data |
| htf | Hydrographic Transfer Format Data |
| htheme | Thinkfree Office NEO Show Theme |
| hti | MXKEY HTI Data |
| htk | HTK Format Parameter File |
| htmenx | Egis Encrypted HTML Data |
| htn | Micrografx Picture Publisher 8 Print Style Data |
| hto | Survex Hierarchical Tagged Objects File |
| htpasswd | Apache Password File |
| htpl | IBM Rational Application Developer WebContent Theme |
| htrc | HTRC Workset Toolkit Configuration Data |
| htri | HTRI Xchanger Suite Data Input |
| hts | HyperTuner Skin |
| htv | HTV Teletekst Data |
| htw | Webhits Template |
| hub | Lattice Reveal Analyzer HUB Data |
| hud | HUD Maker File |
| hud | SmartWare HUD Dictionary Data |
| 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 |