| hbd | HardlinkBackup Backup Definition |
| hbin | HITRAN Binary Output |
| hbk | Hex Workshop Bookmark File |
| hbn | Java Hibernate Data |
| hbp | HBPredicT Output |
| hbs | Line 6 POD HD Edit Set List |
| hbx | BinHex 2.0 Encoded Data |
| hc3 | AquaChem v3 Database |
| hcc | HydroCAD Prefab Chamber |
| hcd | ICM Hourly Climatic Database |
| hce | HydroCAD Hydrograph File |
| hcg | HCLab Document |
| hch | General CADD Hatch |
| hci | HydroCAD IDF Curve |
| hcj | Hashcat Job Data |
| hck | MGS Hinge CK File |
| hcl | HotDocs Clause Archive |
| hcn | X90-OPUS Occupation Data |
| hcr | HydroCAD Rainfall Curve Data |
| hcs | eSubmission Builder Package |
| hcu | HydroCAD Units Definition |
| hcx | BinHex 2.0 Encoded Data |
| hcxs | Health Canada Form Data |
| hd2 | Poser Hand Data |
| hda | HotDocs Auto-Assemble File |
| hda | Houdini Digital Asset Library |
| hdalc | Houdini Indie Digital Asset Library |
| hdanc | Houdini Non-commercial Digital Asset Library |
| hdat | Objective Analysis HDAT Data |
| hdb | HansaWorld Database File |
| hdb | Maple Help Database |
| hdc | HD Tach Benchmark Data |
| hde | HRS Pro Encrypted Secure File |
| hdf | Hierarchical Data Format File |
| hdf4 | Hierarchical Data Format File |