Visual Basic has a number of file extensions that are specific to design time. The currently used file extensions are:
| Extension | Used For |
| .bas | Basic module |
| .cls | Class module |
| .ctl | User Control file |
| .ctx | User Control Binary file |
| .dca | Active Designer Cache |
| .dep | Setup Wizard dependency file |
| .dob | User Document form file |
| .dox | User Document binary form file |
| .dsr | Active Designer file |
| .dsx | Active Designer binary file |
| .frm | Form file |
| .frx | Binary Form file |
| .log | Log file for load errors |
| .oca | Control Typelib Cache |
| .pag | Property Page file |
| .pgx | Binary Property Page file |
| .res | Resource file |
| .swt | Visual Basic Set Up Wizard Template file |
| .tlb | Remote Automation Typelib files |
| .vbg | Visual Basic group project |
| .vbl | User Control Licensing file |
| .vbp | Visual Basic project |
| .vbr | Remote Automation Registration files |
| .vbw | Visual Basic Project workspace |
| .vbz | Wizard launch file |
| .wct | Webclass template file |