| hgf | MOUSE Hydrological File |
| hgm | Sublime Text Data |
| hgt | SRTM Elevation Data |
| hgx | GenX Data |
| hgz | LOCUS Vertical Observation Data |
| hhb | LIGPLOT Hydrogen-bonds Data |
| hhd | STSDAS GEIS Data |
| hhh | STSDAS GEIS Header |
| hhm | HHsearch Database |
| hhr | HHsearch Results |
| hhs | Oracle HyperHub Subkit |
| hi | MAME Highscore Data |
| hi1 | FindinSite Database |
| hi2 | FindinSite Database |
| hi3 | FindinSite Database |
| hi4 | FindinSite Database |
| hi5 | FindinSite Database |
| hi6 | FindinSite Database |
| hi7 | FindinSite Database |
| hi8 | FindinSite Database |
| hi9 | FindinSite Database |
| hia | Spy-CD Database |
| hid2 | KeepSafe Data |
| hif | Quicken Online Data |
| hin | HyperChem Data |
| his | FindinSite Database |
| hisf | DL_POLY Formatted History File |
| hist | MicroStrategy History Data |
| history | Eclipse IDE Local History Data |
| hisu | DL_POLY Unformatted History File |
| hix | PageTech PCLTool Low Level Index File |
| hk | ASCA GIS Housekeeping Data |
| hkdb | iTunes Music Library |
| hkf | Microsoft .NET Install Hook File |
| hkh | HTML-Kit Help File |