What is RAD Basic?
RAD Basic is a modern compiler for the BASIC programming language, fully compatible with Visual Basic 6. It lets you open, compile, and run your existing VB6 projects without converting or rewriting any code.
A modern compiler for VB6 code
RAD Basic is built from the ground up as an independent reimplementation of Visual Basic 6 — similar in spirit to how Wine reimplements the Windows API, or LibreOffice reimplements Microsoft Office file formats. No Visual Basic source code was used in its development.
The result is a compiler that understands VB6 syntax, respects VB6 behavior, and produces native Windows executables — without requiring any Microsoft runtime.
Native VB6 file support
RAD Basic works directly with the files that VB6 produces:
| File type | Extension | Description |
|---|---|---|
| Project file | .vbp |
The main project descriptor |
| Form module | .frm |
Form code and layout |
| Standard module | .bas |
General-purpose code modules |
| Class module | .cls |
Object-oriented class definitions |
You open your existing .vbp project file and compile it directly. There is no conversion step, no migration wizard, and no need to restructure your project.
No migration required
If your project compiles in VB6, it should compile in RAD Basic. The goal is 100% source-level compatibility: the same syntax, the same built-in functions, the same behavior.
This means you can:
- Open a project that was last touched in 1999 and compile it today.
- Make changes and improvements without learning a new language.
- Keep your existing codebase as-is and benefit from a modern compiler toolchain.
Note: RAD Basic is under active development. Some VB6 features may not yet be implemented. Check the Compatibility Matrix to see the current support status.
Native executables
Applications compiled with RAD Basic produce standard Windows PE executables. End users do not need to install any runtime — not the VB6 runtime, and not the .NET runtime. The output file runs on its own.
Note: The RAD Basic IDE and compiler themselves require .NET to run on the developer machine. This is a build-time dependency only and does not affect the programs you produce.
Legal status
RAD Basic is a clean-room reimplementation. The development team has not accessed Visual Basic source code. RAD Basic is written in C and C#, using independent tools such as ANTLR for parsing. It is a legal product, in the same way that other compatibility-layer projects like Wine and ReactOS are legal.