ImageOptim - Faster web pages and apps.
TinyPNG - Make your website faster and save bandwidth. TinyPNG optimizes your PNG images by 50-80% while preserving full transparency!
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.
Oxipng - Oxipng is a multithreaded lossless PNG compression optimizer. It can be used via a command-line interface or as a library in other Rust programs.
TinyJPG - Compress JPEG images with perfect quality and file size
Caesium Image Compressor - Compress your pictures up to 90% without visible quality loss.