Website design can be a tedious, onerous process that requires digging into the back end and changing seemingly infinite minutiae, which is why the FontFit app was born. FontFit lets any user see alternate fonts on any live website--regardless of whether that user has access to the back end of the site in question. The app's goal is to limit the back-and-forth between clients and designers when building a website.
It isn't hard to imagine a scenario wherein the FontFit app would be perfect: for instance, a client likes the font on a particular website and the designer demos that font for the client before making live changes. Conversely, a designer could use the app to show his or her client how they might tweak a preexisting site for their own project.
Regardless of the specific use, the FontFit app can provide a font to save the time of both clients and designers.