Download of batchDPI 2.06 for Mac was on the developer's website when we last checked. We cannot confirm if there is a free download of this app available. We recommend checking the downloaded files with any free antivirus. This Mac application is a product of Jiulong Zhao. The software relates to Design & Photo Tools.
From the developer:
batchDPI can set all pictures in a folder to a uniform DPI of your choice, no matter where they were downloaded or input from or what they were edited with. The program allows you to batch-change the DPI of thousands of pictures with a few simple clicks. The tool will copy (not replace) your photos to ensure the safety of your originals. A special destination folder protects your original files from overwriting.
You may want to check out more Mac applications, such as Smith Chart for Mac, TVPaint Animation or HDR MAX, which might be related to batchDPI.