Features

GnuPG itself is a commandline tool without any graphical stuff. It is the real crypto engine which can be used directly from a command prompt, from shell scripts or by other programs. Therefore it can be considered as a backend for other applications.

However, even when used on the command line it provides all functionality needed - this includes an interactive menu system. The set of commands of this tool will always be a superset of those provided by any frontends.