Optimage - Advanced image optimization tool
E-mage - From developers to developers: a cross-platform tool for losslessly image compression.
ImageOptim API - Web service for image compression
TinyPNG - Make your website faster and save bandwidth. TinyPNG optimizes your PNG images by 50-80% while preserving full transparency!
Let's Enhance - Image upscaling supercharged
JPEGmini - JPEGmini - The Photo Optimization Tool Trusted by Tens of Thousands Image Perfectionists