| dto | Directory Toolkit Output Data |
| dto | Ditto Exported Data |
| dtp | DMDX Binary DTP Data |
| dtr | DATroniC Data Recording |
| dts | Dynatrace AppMon Exported Session Data |
| dtsearch | dtSearch Configuration Data |
| dtsf | Dynatrace AppMon Stored Session Data |
| dtswa | FantasyDVD Player Platinum Data |
| dtsx | Microsoft SQL Server Integration Services Package |
| dtt | Data Transfer To iSeries File |
| dttx | IBM i Access Data Transfer to IBM i |
| dtw | My Better Desktop Layout |
| dtxml | Across DisplayText XML Data |
| dty | Bentley Map Dictionary Data |
| dtyp | DTYPE Database |
| dtype | DTYPE Database |
| dubaskin | Kingsoft Internet Security Skin |
| duc | Action Replay DS Max Save |
| ducf | DinkeyChange Update Code |
| duck | Cyberduck Bookmark |
| dud | DirectUpdate Data |
| duf | DSON User File |
| duh | Autodesk Storm and Sanitary Analysis DUH Data |
| duid | DHCP Unique Identifiers Data |
| dum | CODESYS Device User Management Data |
| dup0 | Samsung Kies Duplicate Media Data |
| dup1 | Samsung Kies Duplicate Media Data |
| dup2 | Samsung Kies Duplicate Media Data |
| dupeguru | DupeGuru Duplicate List |
| dus | Readiris Font Dictionary |