FreeBASIC is a free, open-source BASIC compiler designed for QuickBASIC source compatibility while extending the language for modern systems programming. The current tree builds native or cross-target programs for desktop, Unix, DOS, mobile, browser, embedded, and homebrew-console environments across several 32-bit and 64-bit CPU families. See About FreeBASIC, Main Features, and the current target list.

This manual accompanies the 1.20.4 source tree. Development is ongoing and package availability differs between the official upstream project and the experimental FBXL target packages. Read What's new in 1.20.4, the 1.10 to 1.20 development history, and the package repository guide before assuming that every target is available from every host.

Minimum hardware is listed on the Requirements page. Visit our Installation page for setting up FreeBASIC on your computer.

FreeBASIC is a compiler and as such is not packaged with an IDE (Integrated Development Editor), although there are a few IDE's available. For information on using FreeBASIC without an IDE, see Running.

FreeBASIC is designed to be syntax compatible with QuickBASIC. For best code-compatibility with QuickBASIC, the QB dialect can be used when compiling source code. See FreeBASIC Dialects and Differences from QB.

All official documentation can be found online in the wiki at https://www.freebasic.net/wiki. The online documentation is the most up-to-date resource available. In all cases it can be regarded as the correct version. The downloadable versions of the manual are snapshots of the documentation available at a particular time and should be mostly correct for a specific released version of the compiler. However, we do not maintain multiple versions of the documentation so there may be some discrepancies.