| dmx-info | DriverMax Driver Information |
| dmy | LTSTDB Time Series Data |
| dnb | Microsoft Windows Binary DNS Database |
| dnc | DANCE Database |
| dnd | ClustalW2 Guide Tree Data |
| dne | Netica ASCII Text Data |
| dnet | Netica ASCII Text Data |
| dnk | KillAd Data |
| dnn | DotNetNuke Manifest Data |
| dns | Microsoft Windows DNS Server Database |
| dntu | DameWare NT Utilities Data |
| dnw | EMPOP DrawNetWork Data |
| dock | DragThing Dock Data |
| dockpack | Stardock ObjectDock Package |
| docktheme | Stardock ObjectDock Theme |
| docstore | Adobe Photoshop Lightroom Documentum Cache |
| dod | Progress Artix Data Services Data Model |
| doe | Arena Model File |
| doi | BiRT Data Object Instance |
| dol | Gamecube Executable DOL |
| dom | DIMPLOT Domain Definition |
| don | PLS-CADD Lines and Annotation Data |
| dop | DxO Optics Pro Sidecar File |
| dop | DOpus Toolbar File |
| doq | Digital Orthophoto Quadrangle Data |
| dot | Ribbons Dot Definition |
| dov | BiRT Actuate Query Definition File |
| dp1 | DataPower Database |
| dp2 | DatePad 2 Data |
| dp4 | Actuate Analytics Cube Profile |
| dpatch | Dpatch Patch Data |
| dpb | DataPilot Data |
| dpcache | Apple iPhoto Desktop Photos Cache |
| dpe | DPwinEHE Calculation |
| dpf | F-Secure Default Policy File |