Download of ExifTool 13.0 for Mac was available from the developer's website when we last checked. We cannot confirm if there is a free download of this app available.
According to the results of the Google Safe Browsing check, the developer's site is safe. Despite this, we recommend checking the downloaded files with any free antivirus software. ExifTool for Mac lies within Developer Tools, more precisely Webmaster Tools. The actual developer of this free Mac application is Phil Harvey.
From the developer:
ExifTool is a platform-independent Perl library plus a command-line application for reading, writing, and editing meta information in a wide variety of files. ExifTool supports many different metadata formats, as well as the maker notes of many digital cameras.
You may want to check out more Mac applications, such as ExifChanger, pyExifToolGui or PhotoGrok, which might be related to ExifTool.