This FTP client separates the program core from the GUI by using a protocol between both parts.
The core is written in C, and implements most of the FTP command to be able to browse FTPs, download and upload files.
It implements a global queue for downloads, multiple server connections, bookmarks, etc.
A command line interface is present as well as a telnet interface.
Interfaces written in other programming languages (for example Java, GTK, etc.) may be created to get the software more user friendly.