2 file types use the .fl file extension.

What is an FL file?

Save file created by Freelancer, a game where players adventure through missions as mercenaries in outer space; contains a saved game state, either manually or auto-saved; used to save and load in-game progress.

Category: Game Files

FLUID GUI Design

An FL file may also be a graphical user interface (GUI) design created by FLUID (Fast Light User-Interface Designer), a GUI builder included with the Fast Light Toolkit (FLTK). It contains FLTK source code, which FLUID uses to show UI elements to developers. FL files are meant to be compiled into .CXX and .H files, before being included in a program.

FLTK is a multiplatform C++ toolkit used to develop GUIs. One of the tools FLTK includes is FLUID, a visual GUI builder.

Developers use FLUID to create and edit GUIs using FLTK's included GUI widgets. FLUID projects are saved in FL files, which are comprised of FLTK source code. Typically, developers compile FL files into CXX and H files, using the command-line or in-app FLUID compiler, before including them in applications. However, an FL file can also be used to create a simple program, if all the program's code is contained in the FL file.

FL files are meant to be opened in FLUID (multiplatform). To open an FL file in FLUID, select File → Open... from the program's menu bar.

Because FL files are plain text source code files, you can also open them in any text or source code editor, such as Microsoft Visual Studio Code (multiplatform).

Programs that open FL files

Updated: May 4, 2022