| hf | RayShade HeightField Format |
| hfd | HotDocs Form Document |
| hft | HotDocs Envoy-based Form Template |
| hht | Help and Support Center HHT |
| hip | Houdini Scene |
| hiplc | Houdini Limited Commercial Scene |
| hipnc | Houdini Apprentice |
| hjt | Treepad v6 Database |
| hlp | Windows Help File |
| hlz | MultiEdit Packed Help File |
| hmk | Hallmark Card Studio Document |
| hmw | Homeword for DeskMate Document |
| hnc | NoteCenter Notes Document |
| hne | NoteCenter Encrypted Notes Document |
| hou | ARCHLine v4 Drawing |
| hp8 | HP NewWave Write Text |
| hpd | HotDocs PDF Document |
| hpl | HotDocs Answer Source |
| hpo | HippoDraw Canvas Document |
| hpt | HotDocs PDF-based Form Template |
| hrx | Herolab E.A.S.Y Document |
| hsf | HOOPS Stream File |
| htc | HTML Component |
| htd | HyperTRANSCRIBE Document |
| htext | WebKNotes HTXT Document |
| htm | Hypertext Markup Language Document |
| htmhjt | Treepad v6 Text Database |
| html | Hypertext Markup Language Document |
| htx | Extended HTML Template |
| htxt | WebKNotes HTXT Document |
| hus | Husqvarna Viking Embroidery Design |
| hvs | Cubicon Cubicreator G-Code |
| hwp | Hangul Word Processor Document |
| hwpx | Hangul Word Processor 2010 Document |
| hxl | Microsoft Help 2 Registered Namespace List |
