TinyPNG - Make your website faster and save bandwidth. TinyPNG optimizes your PNG images by 50-80% while preserving full transparency!
Optimus.io - Lossless image optimization
Image Compressor by RedKetchup - Compress the file size of a PNG, JPEG, WEBP, or HEIC image online. Reduce the image dimensions based on KB or MB. Improve the quality of PNG compression with dithering.
OptiMole - Optimole makes your images weigh even 80% less while looking just as good!
TinyJPG - Compress JPEG images with perfect quality and file size
Caesium Image Compressor - Compress your pictures up to 90% without visible quality loss.