Fonty scans all the fonts installed on your Mac and lists their character support. The tool comes with some predefined character sets for some common languages and groups of characters.
Fonty was designed to help graphic designers choose appropriate fonts for multilingual artworks, those with the right characters for all required languages. However, the character sets don't necessarily have to be language specific. You can create your own character sets with whatever set of characters you like, such as currency, scientific symbols, braille, etc.