What are some alternatives?
Lepton - Lepton image compression: saving 22% losslessly from images at 15MB/s
iLoveIMG - iLoveIMG is one of most powerful solution that comes with all the major tool you cloud want to edit images in bulk.
File Converter - Convert & compress everything in 2 clicks!
TinyPNG - Make your website faster and save bandwidth. TinyPNG optimizes your PNG images by 50-80% while preserving full transparency!
ImageOptim - Faster web pages and apps.
Photo Size Optimizer - Photo Size Optimizer for Mac is a powerful photo resizer and optimizer to optimize photos by 80% ~ 20%.