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.
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.
OptiPNG - OptiPNG is a command-line PNG optimizer that recompresses image files to a smaller size, without...
TinyJPG - Compress JPEG images with perfect quality and file size
TruePNG - Command-line PNG optimizer.