What are some alternatives?
When comparing Phatch and FileOptimizer, you can also consider the following products
XnConvert - XnConvert is an easy image converter for graphic files, photos and images available on Windows...
ImageOptim - Faster web pages and apps.
FastStone Photo Resizer - Convert and Rename images in batch mode Support JPEG, BMP, GIF, PNG, TIFF and JPEG2000
pngquant - command-line utility and library for lossy compression of PNG images
Caesium Image Compressor - Compress your pictures up to 90% without visible quality loss.
PhotoBulk - PhotoBulk is a bulk image editor for Mac that was created for the best experience of batch editing. With this image editing software for macOS you can add watermarks, optimize and resize pictures, convert images or rename photos in bulk.