{{implementation|BASIC}}'''FreeBASIC''' is a free/[[open source]] (GPL), 32-bit BASIC compiler for [[Microsoft]] [[Windows]] (32-bit), protected-mode DOS (DOS extender), the Xbox and [[Linux]] (x86), and is being ported to other platforms.
It makes use of the GNU binutils programming tools as backends and can produce console, [[QuickBASIC]]-compatible graphical and [[GUI]] executables, besides dynamic and static libraries. A [[GCC]] frontend is currently being developed, which will enable compilation for many more operating systems than currently supported.
Currently, software libraries like [[GTK+]], GSL, [[:Category:SDL|SDL]], Allegro, [[Lua]] and [[OpenGL]] can be used directly (no wrappers, only function and structure prototypes), and more are being added on every new release. A complete set of the Windows API headers is also included.
The compiler, and its nearly 90,000 lines of code, was, and still is, compiled by itself (FreeBASIC is a self-hosting compiler). The first version of FreeBASIC was written in [[Visual Basic]] for DOS for that purpose.