| hdr | DataFlex Database Header |
| hdr | Microsoft IIS NNTP Header Data |
| hdr | Mail.dat Header File |
| hdu | FM-ONE User Data |
| hdumx | HotDocs User Mapping XML |
| hdz | Poser Compressed Hand Data |
| he2 | Hierarchical Data Format File |
| he4 | Hierarchical Data Format Release 4 Data |
| he5 | Hierarchical Data Format Release 5 |
| hea | PhysioBank Header File |
| hec | Pvquan Heckbert Data |
| hedata | HTML Executable Publication Data |
| hef | HEAT Export Data |
| heg | GRABLOX HEG Data |
| heinf | HippoEDIT File Information |
| heo | NASA Solve getpar Earth Orientation Data |
| hep | Hummingbird HostExplorer Profile |
| heu | Adobe Flash Player Cache Metadata |
| hewsp | HippoEDIT Workspace |
| hex | BinHex Encoded Data |
| hexbook | HHD Hex Editor Bookmarks Data |
| hf2 | L3DT Compressed Heightfield Data |
| hff | L3DT Heightfield Data |
| hfg | HeroForge-Anew Character Data |
| hfo | Pinnacle Hollywood FX Object |
| hfx | Hot Fax Data |
| hfz | L3DT Compressed Heightfield Data |
| hgc | PC Fold Data |
| hgc | Zeus 5.0 Physical Data |
| hgdata | Altair HyperGraph Data |
| hgf | HomeGauge Form File |
| hgf | MOUSE Hydrological File |
| hgm | Sublime Text Data |
| hgt | SRTM Elevation Data |
| hgx | GenX Data |