A computer system provides a plug-in architecture for creation of a dynamic font. The computer system can incorporate a new filter function into a filtering layer of a font program. The filtering layer includes pre-defined filter functions to transform a base font into a new font. The computer system applies one or more font rules in the filtering layer to the base font. The font rules are implemented by the new filter function and at least one of the pre-defined filter functions to randomize an appearance of each character in a character string. The character string rendered with the new font has a dynamic and randomized appearance.