BatchRename Flex 4.5.1 for Mac could be downloaded 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. The application is categorized as System Tools. This free software for Mac OS X is an intellectual property of WilliamSoftware.
From the developer:
The award-winning professional renaming app comes to Mac now! Rename a batch of files and folders with all kinds of customizable and flexible renaming rules in just a few clicks. Especially, rename media files (MP3, M4A, MP4) with media tags, rename photos using EXIF, IPTC tag, or encrypt your file names with RC4 or AES.
You may want to check out more Mac applications, such as Mobile-Flex, flex sdk 3 or Flex Projector, which might be related to BatchRename Flex.