| Extension | File Type | Files scanned | Contributor |
| H2O | Liquid Entertainment H2O compressed archive | 3 | |
| H5 | HDF5 data file | 14 | |
| HA | HA compressed archive | 5 | |
| HAP | Hamarsoft HAP 3.x compressed archive | 3 | |
| HBK | Hex Workshop Bookmark File | 6 | .Cryorb |
| HCC | HydroCAD Data for prefabricated storage Chambers | 7 | |
| HCG | HCLab document | 8 | |
| HCP | HydroCAD Project | 12 | |
| HDF | NCSA Hierarchical Data Format | 13 | |
| HDP/WDP/WMP | JPEG XR (AKA HD Photo, Windows Media Photo) | 4 | |
| HDR | InstallShield setup header | 19 | |
| HDR | Radiance High Dynamic Range image | 10 | |
| HE5 | Hierarchical Data Format Release 5 | 43 | |
| HES | Hudson Entertainment Sound | 8 | |
| HFA | ERDAS Imagine Hierarchical File Architecture | 7 | |
| HFZ | HollywoodFX Plug-In | 17 | kif aka AC |
| HG1 | Hellgate London save game | 4 | |
| HIP | HiP compressed file | 3 | |
| HIPC | Hippel-COSO Music | 39 | |
| HIR | C64 Hires bitmap | 4 | |
| HIV/DAT | Windows NT Registry Hive | 4 | |
| HJT | TreePAD document | 9 | Renan |
| HJT | TreePAD document (older version) | 18 | |
| HKI | WinHki compressed archive | 3 | |
| HLF | FAR help | 18 | |
| HLP | HP200LX System Application's Help | 15 | |
| HLP | Microsoft Advisor Help file | 15 | |
| HLP | Windows HELP File | 201 | Davide "Airex" Airaghi |
| HLX | Help Magician text file | 8 | |
| HMK | Hallmark Card Studio file | 15 | |
| HMP | Frontier 2 First Encounters Music | 17 | |
| HMP | Help Magician Project | 2 | |
| HMT | HighMAT file | 7 | |
| HMW | Homeword for DeskMate | 3 | |
| HND | HNSKY Deep Sky Database | 9 | |
| HNE | NoteCenter encrypted notes | 2 | |
| HOG | Descent game data archive | 2 | |
| HPD | HP Document | 25 | |
| HPI | Hemera Photo-Object Image | 2048 | Haakon Birkeland |
| HPI | Total Annihilation saved game | 3 | |
| HPS | HP HPS digital sender info | 3 | |
| HQX | BinHex encoded | 9 | |
| HRF | Hitachi Raster Format bitmap | 15 | |
| HRT | Hornet Packer module/song | 2 | |
| HRU | HRU bitmap | 21 | |
| HSB | HandStory eBook | 6 | |
| HSC | HSC music composer song | 62 | |
| HSC | HYSYS Simulation Case | 5 | |
| HSI/JPG | HSI JPEG bitmap | 6 | |
| HT | HyperTerminal data file | 10 | |
| HTC | HTML Component (ASCII) | 7 | |
| HTC | HTML Component (Unicode) | 7 | |
| HTM/HTML | HyperText Markup Language with DOCTYPE | 134 | |
| HTML | HyperText Markup Language | 33 | |
| HTR/HAPTAR | Haptek Compressed file | 10 | |
| HUD | HUD Maker | 4 | |
| HUH | HydroCAD Unit Hydrograph definitions | 4 | |
| HUS | Husqvarna Designer I Embroidery Machine Format | 6 | FILExt |
| HWP | Hangul (Korean) Word Processor document | 7 | |
| HWP | Hangul (Korean) Word Processor document (alternate) | 27 | |
| HXS | Microsoft compiled help format 2.0 | 102 | |
| HXT | Help Table of Contents | 4 | |
| HYP | Atari ST Guide Hypertext document | 5 | |
| HYP | Hyper compressed archive | 4 | |
| HZF | neosat fixes | 12 | |
