TinyPNG - Make your website faster and save bandwidth. TinyPNG optimizes your PNG images by 50-80% while preserving full transparency!
FILEminimizer Pictures - FILEminimizer Pictures compresses JPEG photos, TIFF, BMP and PNG images and pictures by up to 98%.
Optimus.io - Lossless image optimization
OptiMole - Optimole makes your images weigh even 80% less while looking just as good!
Compressor.io - Optimize and compress your images online. Compressor is a lossy and lossless photo compression tool.
TinyJPG - Compress JPEG images with perfect quality and file size