Photoshop.com - Photoshop.
TinyPNG - Make your website faster and save bandwidth. TinyPNG optimizes your PNG images by 50-80% while preserving full transparency!
piZap - Free online photo editing software.
ImageOptim - Faster web pages and apps.
Phixr - Phixr is a free online photograph proofreader, an instrument for editing your photos in your web program.
TinyJPG - Compress JPEG images with perfect quality and file size