/System/Applications/Font Book.app/Contents/MacOS/Font Book Allows users to view and organize their fonts, to remove duplication, and to find other fonts. It also provides a feature to validate fonts, to ensure that they are not corrupt and not being used in any profession to make sure fonts can be used safely. Font Book will maintain a library of all installed fonts, whether they are installed globally as part of the operating system, or they are only specific to a user account.