| da | Gcov Compiled Output |
| dabriefcase | RemObjects Data Abstract File Briefcase |
| daconfig | RemObjects Data Abstract Configuration |
| daconnections | RemObjects Data Abstract Connections Data |
| dad | RemObjects Delphi Data Abstract Driver |
| dadiagrams | RemObjects Data Abstract Data Diagrams |
| dadx | Eclipse Document Access Definition Extension |
| dart | Dart Source Code |
| daschema | RemObjects Data Abstract Schema |
| db2tbl | Microsoft Visual Studio DB2 Table Script |
| db2udf | Visual Studio DB2 User Defined Function Data |
| dbag | WinSQL DataBag Data |
| dbg | Microsoft Visual Studio Debug File |
| dbgdt | IAR System Debugger Desktop Data |
| dbgsym | Pidgin IM Debug Symbols Data |
| dbi | Data Explorer Information |
| dblink | Altium Designer Database Link |
| dblog | Debugview++ Debug Log |
| dbml | Database Markup Language File |
| dbo | DarkBASIC Object |
| dbp | Visual Studio Database Project |
| dbproj | Visual Studio 2010 Database Project |
| dcf | ProWorx NXT Database Configuration |
| dci | RAD Studio Delphi Code Insight |
| dcp | Delphi Component Package |
| dcr | Delphi Component Resource |
| dct | Delphi Component Template |
| dcu | Delphi Compiled Unit |
| dcuil | Delphi .NET Compiled Unit |
| dcurl | Curl Detached Applet |
| dda | GLBasic ASCII Scene Data |
| ddb | ProWorx NXT Descriptor Data with Blocking |
| ddd | Alpha Five Data Dictionary |
| ddf | ProWorx NXT Descfriptor Data File |
| ddf | Diamond Directive File |