| .h | C/C++ Header Format |
| .h++ | Unusual C++ Header |
| .h-263 | H.263 Encoded Video |
| .h.263 | H.263 Encoded Video |
| .h0 | Magix Music Studio Format |
| .h00 | ARM EPROM HEX |
| .h01 | ARM EPROM HEX |
| .h04 | GE FIX32 Historical |
| .h08 | GE FIX32 Historical |
| .h10 | At Home Canada 2010 Tax Return Format |
| .h11 | At Home 2011 Tax Return Format |
| .h12 | At Home 2012 Tax Return Format |
| .h1c | Windows Vista File Related To Assistance Platform (AP) Help |
| .h1d | Microsoft Windows |
| .h1f | Microsoft Windows Assistance Platform Client Help |
| .h1h | Microsoft Windows Merged Hierarchy Help |
| .h1k | Keyword Index - Microsoft Windows Assistance Platform Client Help Related |
| .h1q | Microsoft Help Merged Query Index Format |
| .h1s | Microsoft Windows Assistance Platform Client Help Format |
| .h1t | Microsoft Windows Assistance Platform Client Help Related |
| .h1v | Task Metadata - Microsoft Windows Assistance Platform Client Help Related |
| .h1w | Microsoft Windows Keyword Index |
| .h260 | Video Recording |
| .h261 | H.261 Video Format |
| .h263 | H.263 Video Format |
| .h264 | H.264 Video Format |
| .h2drumkit | Hydrogen Drum Kit |
| .h2o | Battle Realms Game Data Format |
| .h2p | Zebra Preset |
| .h2song | Hydrogen Drum Notes |
| .h2w | H2testw |
| .h3b | POD HD300 Bundle |
| .h3c | Heroes Of Might And Magic 3 Campaign |
| .h3d | Altair HyperView 3D Model |
| .h3e | POD HD300 Preset |
| .h3m | Heroes Of Might And Magic 3 Map Format |
| .h4b | POD HD400 Bundle |
| .h4e | POD HD400 Preset |
| .h4m | Resident Evil Zero Game |
| .h4r | Heroes Of Might And Magic 4 Data Format |
| .h5 | Hierarchical Data Format Version 5 |
| .h5e | POD HD500 Preset |
| .h5s | POD HD500 Set |
| .h86 | CP/M |
| .ha | HA Compressed Archive |
| .hak | BioWare Aurora Engine |
| .hal | HansaWorld Enterprise HAL Code Format |
| .ham | Descent 2 Resource Format |
| .haml | HTML Abstraction Markup Language |
| .handlebars | Handlebars Template |
| .hang | Apple Mac OS X Terminal |
| .hap | HAP Compressed File Archive |
| .har | E-Sword Harmony Resource |
| .harddisk | Boxer For Mac Harddisk |
| .harx | E-sword Harmony |
| .has | Haskell Script Format |
| .hash | EnCase Forensic Drive Image Hash |
| .hat | Formula 1 Car Race 2001 Log Hat |
| .hathdl | Hentai@Home Download |
| .hav | Video Recorder Video |
| .haz | Microsoft Flight Texture |
| .hbc | HyperBac Compressed Archive Format |
| .hbc2 | HyperBac Compressed Archive |
| .hbe | HyperBac Compressed/encrypted Archive |
| .hbk | Mathcad Handbook Format |
| .hbm | Hibernate Script |
| .hbn | Java Hibernate |
| .hbr | HaxBall Replay |
| .hbx | BinHex Compressed File ASCII Archive |
| .hbz | StarMoney Macro |
| .hcb | HyperOS Compressed Backup |
| .hcc | HydroCAD Storage Chamber Definition Format |
| .hce | HydroCAD Hydrograph Data Format |
| .hcf | Compact Ham Library |
| .hcfg | HoDokK Configuration |
| .hcg | HClab Chart |
| .hci | HydroCAD IDF Data Format |
| .hcl | HotDocs Library Format |
| .hcom | Sound Tools HCOM Audio |
| .hcp | HydroCAD Project Format |
| .hcr | HydroCAD Stormwater Modeling System Rainfall Definition |
| .hcs | NHP ESubmission Builder Submission Package |
| .hct | Symantec LiveUpdate |
| .hcu | HydroCAD Hydrograph Units Definitions Format |
| .hcw | HTML Help Workshop Conversion Wizard Macro |
| .hcx | Harvard ChartXL Chart Format |
| .hd2 | Poser Hand Pose Format |
| .hda | HotDocs Document File Format |
| .hdb | HansaWorld Enterprise Database Format |
| .hdc | HD Tach Benchmark |
| .hdd | Parallels Workstation Virtual Hard Disk Format |
| .hde | NAUPA File Encryptor Encrypted |
| .hdf | Hierarchical Data Format |
| .hdf4 | HDF4 |
| .hdf5 | HDF5 |
| .hdi | Autodesk AutoCAD Heidi Device Interface |
| .hdk | HotDocs Registration Format |
| .hdl | Procomm Plus Alternate Download Format Listing Format |
| .hdm | HDML Handheld Device Markup Language Format |
| .hdml | Handheld Device Markup Language |
| .hdmov | Apple QuickTime HD Movie Format |
| .hdmp | Microsoft Windows Heap Dump Format |
| .hdp | HD Photo |
| .hdpmx | HotDocs Publisher Mapping XML Format |
| .hdr | High Dynamic Range Image Format |
| .hdrp | HDRtist Graphic Format |
| .hdru | Apollo HRDU Image Format |
| .hds | Windows Digital Right Management Format |
| .hdt | Photoshop HDR Toning Preset Format |
| .hdumx | HotDocs User Mapping XML Format |
| .hdv | High Definition Video Format |
| .hdx | Delphi MultiHelp Index Format |
| .hdz | Poser Compressed Hand Pose Format |
| .he4 | HDF4 |
| .hea | Fifa 2001 Data |
| .heartssave-ms | Hearts Saved Game Format |
| .heb | DEcomp 3D Scene Data |
| .hed | Hi-Eddi Image |
| .hef | HEAT Export |
| .help | Unix Help Format |
| .helpcfg | Adobe AIR Help Configuration |
| .helpindex | Mariner Software Narrator Index |
| .hep | Novell NetWare Help Librarian Data |
| .hes | TurboGrafx-16 Audio |
| .het | WinSQL HTML Export Template |
| .heu | Adobe Flash Player Cache Metadata |
| .hex | Hex Dump Format |
| .hf | HF Image Format |
| .hfa | Erdas Imagine Hierarchical |
| .hfb | Hell Fighter Battle |
| .hfc | H-JTAG Configuration |
| .hfd | HotDocs Form Document Format |
| .hfmx | HFM.NET Configuration |
| .hfo | Pinnacle Hollywood FX Object |
| .hfp | XnView Filter |
| .hfs | MacImage Macintosh HFS Disk Image Format |
| .hfss | Ansoft HFSS Project |
| .hft | HaftiX Cross-stitch Pattern |
| .hfv | Virtual Mac Hard Drive Format |
| .hfx | Harvard Graphics F/X |
| .hg | HP Graphics Language |
| .hg1 | Hellgate: London Saved Game |
| .hgd | IP Camera Video |
| .hgh | Star Wars: Tie Fighter High Score |
| .hgl | Hewlett-Packard Graphics Language Format |
| .hgp | HighGrow Plant |
| .hgs | Harvard Graphics Graphic |
| .hgt | Shuttle Radar Topography Mission Data SRTM Format |
| .hgz | ArcMap GIS |
| .hh | C++ Header Format |
| .hhc | HTML Help Table Of Contents Format |
| .hhh | Power C Precompiled Header Format |
| .hhk | Microsoft HTML Help Index Format |
| .hhl | Visual Basic |
| .hhp | Microsoft HTML Help Project |
| .hhpack | HTC Home Extension |
| .hhs | Microsoft HTML Help Workshop Sample |
| .hhsl | Hockey High Score List Format |
| .hht | Microsoft Help And Support Center HHT Format |
| .hi | High Scores Format |
| .hic | HicEst Script |
| .hid | Sony Ericsson Configuration Archive Format |
| .hid2 | KeepSafe Encrypted |
| .hif | Quicken Online Format |
| .hil | Deluxe Ski Jump 3 Hill |
| .him | ROSE Online Highmaps |
| .hin | HyperChem HIN Chemical Modeller Input |
| .hip | Houdini Project Format |
| .hipnc | Houdini Apprentice Format |
| .hips | Bitmap |
| .hir | Hires C64 Image Format |
| .his | FindinSite Database Definition Format |
| .hisawsave | Nancy Drew Saved Game |
| .hisf | DL_POLY History |
| .history | Eclipse IDE Local History |
| .hisu | DL_POLY History |
| .hit | The Sims Sound Format |
| .hiv | Windows NT Registry Hive |
| .hjt | TreePad Editor Format |
| .hkc | HTML-KIT Auto Complete Short Cut |
| .hkdb | Apple ITunes Database Format |
| .hke | Painkiller Overdose Game |
| .hkf | Microsoft.NET Framework |
| .hki | WinHKI Compressed Archive Format |
| .hki1 | WinHKI HKI1 Compressed Archive Format |
| .hki2 | WinHKI HKI2 Compressed Archive Format |
| .hki3 | WinHKI HKI3 Compressed Archive Format |
| .hkl | RMCProfile Range Of Values |
| .hkm | Havok Movie Format |
| .hks | HTML-KIT Plugin |
| .hkx | Skyrim Animation |
| .hl | HeuristicLab Storage Format |
| .hl$ | MS-DOS Compressed Help |
| .hl1 | Half-Life Saved Game |
| .hl6 | Horizontal.Log 6 |
| .hla | High Level Assembler Source |
| .hlb | VAX VMS Help Library Format |
| .hlc | ESO MIDAS Help Command |
| .hld | Structural Desktop Hold |
| .hlf | FAR Manager Help |
| .hlk | Warhammer 40k Dawn Of War 2 Animation |
| .hln | MicroStation Hidden Line |
| .hlog | VMware Workstation Log |
| .hlp | Help Format |
| .hlq | ESO MIDAS Help Qualifier |
| .hlsl | High Level Shader Language Source Code Format |
| .hlt | Watcher Database Trades List |
| .hlw | Win32/AMalum.EDHZ |
| .hlx | ATI Radeon Video Driver Format |
| .hlz | MultiEdit Packed Help |
| .hm | Windows Help Context IDs |
| .hm0 | MAGIX Audio Cleaning Lab Waveform |
| .hm2 | Help & Manual Help File Project |
| .hm3 | Help & Manual Help File Project |
| .hma | Sony MiniDisc Audio Format |
| .hmap | Microsoft SharePoint Server 2007 Temporary |
| .hmap.Dir | Microsoft SharePoint Server 2007 Temporary |
| .hmax | Custom 3ds Max Format |
| .hmd | SWAT Relative Humidity Input |
| .hme | Smartphone Theme Format |
| .hmf | HOOPS Metafile |
| .hmgd | Microsoft Grammar |
| .hmhd | Word Hyphenation Format |
| .hmi | HMI Audio Format |
| .hmk | Hallmark Card Studio Card Format |
| .hml | HostMonitor TestList Format |
| .hmmer | SAM HMMER Format |
| .hmmr | SAM HMMR |
| .hmp | Worms Height Map Format |
| .hms | HostMonitor Script Format |
| .hmsd | Microsoft Dictionary |
| .hmskin | Help & Manual Help File Skin |
| .hmt | HighMAT Format |
| .hmx | Help & Manual Help File Project |
| .hmxp | Help & Manual Help File Uncompressed XML Project |
| .hmxz | Help & Manual Help File Compressed XML Project |
| .hmy | Hemingway Content Management System Plugin |
| .hm~ | Help&Manual Help Project Backup |
| .hnc | NoteCenter Note |
| .hnd | HNSKY Deep Sky Database |
| .hnf | HNF Split & Merge Channels |
| .hnr | Teleatlas |
| .hob | Star Trek Birth Of The Federation Ship Graphic Data |
| .hod | Homeworld Object Data |
| .hog | Descent Hog Format |
| .hogg | Cryptic Studios Data |
| .hol | Microsoft Outlook Holiday Calendar Format |
| .honmod | Heroes Of Newerth Mod Format |
| .hop | Hippon Protected |
| .hot | The Sims Sound Format |
| .hotspot | Homeworld Cursor Informaiton |
| .hp | HP Graphics Language Plotter |
| .hp1 | HP Graphics Language Plotter |
| .hp2 | HP Graphics Language Plotter |
| .hp? | LoseThos C+ Header |
| .hpc | System Dynamic Library |
| .hpd | HotDocs PDF Document Format |
| .hpf | High Performance FORTRAN Format |
| .hpfs | OS/2 High Performance File System |
| .hpg | HP Graphics Language Plotter Format |
| .hpgl | Hewlett Packard Graphics Language Plot Format |
| .hpgl2 | Hewlett Packard Graphics Language 2 |
| .hpi | Hemera Photo Image Format |
| .hpj | Microsoft Win Help Project Format |
| .hpk | Haemimont Games Game Package Format |
| .hpl | Hewlett-Packard LaserJet Vector Image Format |
| .hplg | Apple ITunes Device Plugin |
| .hpm | Procomm Plus Alternate Main Menu |
| .hpo | HippoDraw Canvas Document |
| .hpp | C++ Header Format |
| .hpr | RoboHelp Settings |
| .hprj | Heroglyph Project |
| .hprof | Java Heap Dump |
| .hps | HPL2 Script |
| .hpt | HotDocs PDF Template Format |
| .hpx | MetaVR 3D Model |
| .hpz | Helpinator Project |
| .hqf | QuiltCAD Stitch |
| .hqr | Little Big Adventure HQR |
| .hqx | Macintosh BinHex Archive |
| .hr | TRS 80 Image File Format |
| .hr2 | Poser Hair Format |
| .hrc | Autodesk Softimage Model 3D |
| .hrd | MSC Patran Device-dependent Hardcopy |
| .hrf | Hitachi CADCore Raster Format |
| .hrl | Erlang Source Or Script Format |
| .hrm | Polar ProTrainer Pulse Rate Save |
| .hrs | Holder Reporting System |
| .hru | HRU Image Format |
| .hrx | Herolab EasyWin32 |
| .hrz | Poser Compressed Hair Format |
| .hs | Literate Haskell Source Code Or Script Format |
| .hs2 | HyperRESEARCH Postering Monochrome Image Format |
| .hsb | HALion Sampler Format |
| .hsc | Aspen HYSYS Simulation Format |
| .hse | Adobe Dreamweaver Snippet |
| .hsf | HOOPS Stream Format |
| .hsh | Windows Catalog Search Index Format |
| .hsi | Handmade Software Bitmap Image |
| .hsk | Nimbus 7 SAMS Data Format |
| .hsm | The Sims Sound |
| .hsp | HSC Composer Packed By Number Six |
| .hsql | HtmSQL Html |
| .hsr | RezeptAssist Import Or Export |
| .hss | Adobe Dreamweaver Snippet |
| .hst | Yahooo Messenger History Format |
| .hstx | Altair HyperStudy Package |
| .hsv | Diablo: Hellfire Singleplayer Character Data |
| .hsx | Health & Safety Xpert Project |
| .ht | HyperTerminal Session Format |
| .ht1 | Google Desktop Application Data |
| .ht4 | HTML Version 4 |
| .hta | HTML Program Format |
| .htaccess | Apache Access Configuration Format |
| .htb | Audacity Help Format |
| .htc | HTML Component Format |
| .htd | Adobe ExtendScript HTML |
| .htg | HackTheGame Mission Pack Format |
| .htgroup | Apache Server User Group |
| .hti | Microsoft Windows WinHelp Related |
| .htk | Hidden Markov Model Toolkit Speech Recognition |
| .htm | HTML Hypertext Markup Language Web Page Format |
| .html | HTML Hypertext Markup Language Web Page Format |
| .html0 | Book Designer E-book Format |
| .html5 | HTML5 Hypertext Markup Language Revision 5 Source |
| .htmlenx | Egis Encrypted HTML |
| .htmls | HyperText Markup Language Document With Server-side Include |
| .htmlz | Zipped HTML Format |
| .htms | PHP HTML Document |
| .htn | Micrografx Picture Publisher 8 Print Style |
| .htp | Autodesk Slope Template Definition |
| .htpasswd | Apache Access Configuration Format |
| .htpl | IBM Rational Application Developer WebContent Theme |
| .htr | Microsoft Windows NT Password Services Script |
| .htri | HTRI Xchanger Suite Data Input |
| .htt | Microsoft HyperText Template Format |
| .htw | Windows |
| .htx | Microsoft FrontPage Database Results |
| .htxt | Hanvon WISEreader E-book Format |
| .htz4 | HyperMaker Publication Format |
| .htz5 | HyperMaker Document Format |
| .hud | SmartWare Dictionary |
| .huh | HydroCAD Unit Hydrograph Definitions Format |
| .hul | Re-Volt Collision Data |
| .hull | Half-Life Map Collision Hull |
| .hun | Personal Paint Hungarian Language User Interface |
| .hup | Haihaisoft DRM-X Protected Video |
| .hus | Husqvarna Embroidery Format |
| .huv | Husqvarna Viking Designer Graphic |
| .hv | Microsoft Windows Mobile Hive |
| .hva | Command And Conquer Tiberian Sun Voxel Animation Control |
| .hvc | ASCII Format |
| .hvd | HoverDesk Theme |
| .HVIF | Haiku Vector Icon Format |
| .hvl | Commodore Amiga HivelyTracker Audio Module |
| .hvpl | Apple ITunes Visual Plugin Format |
| .hwd | Hedgewars Game Replay Format |
| .hwl | Corel WordPerfect Shared Writing Tools 9.0 |
| .hwmap | Hedgewars Drawn Map Format |
| .hwof | Microsoft Office For Mac Help |
| .hwp | Hangul Document Format |
| .hws | Hedgewars Saved Game Format |
| .hwt | Huawei Ascend P6 Emotion UI Theme |
| .hwx | RSNetWorx Registration |
| .hx | Haxe Source Code |
| .hxa | Microsoft Help Attribute Definition Format |
| .hxc | Microsoft Visual Studio Collection Definition Format |
| .hxd | Microsoft Help Validator |
| .hxe | Microsoft Help 2 Sample Definition Format |
| .hxf | Microsoft Help Include |
| .hxh | Microsoft Help Merged Hierarchy |
| .hxi | Microsoft Help Compiled Storage |
| .hxk | Microsoft Help 2 Keyword Index Format |
| .hxl | Microsoft Help Registered Namespace List |
| .hxm | Descent 2 Resource Modification Format |
| .hxml | HaXe Make |
| .hxn | Hexagon Model Format |
| .hxp | HaXe Project |
| .hxproj | FlashDevelop Flash Project |
| .hxr | Microsoft Help Data |
| .hxs | Microsoft Help Compiled Storage Format |
| .hxt | Help Table Of Contents Format |
| .hxv | Microsoft Help Virtual Topic Definition |
| .hxw | Microsoft Help Attribute Definition |
| .hxx | C++ Header Format |
| .hy1 | Ventura Publisher Hyphenation Algorithm |
| .hy2 | Ventura Publisher Hyphenation Algorithms |
| .hyc | Corel WordPerfect Data |
| .hyd | Corel WordPerfect Hyphenation Dictionary |
| .hydra | Hydra Image Filter Program Format |
| .hym | Hymarc Scandata Scanner 3D Image Binary |
| .hyp | Adobe Acrobat Dictionary Format |
| .hype | Hype Web Project Format |
| .hyq | CARE-S InfoWorks Hydrograph |
| .hyv | HY-TEK Sports Team Manager Meet Event Format |
| .hz | Chinese (Hanzi) Text |
| .hzd | SeisWorks |
| .h_ | Microsoft Winhelp Compressed |
| .h__ | C++ Header |
