Audio Shop : Your friendly neighborhood script for mangling images or video using audio editing tools.
Trimage (lossless) image compressor : Trimage is a cross-platform GUI and command-line interface to optimize image files via optipng, pngcrush, advpng and jpegoptim
Squoosh : Squoosh is an image compression web app that allows you to dive into the advanced options provided by various image compressors.
PunyPNG : PunyPNG is a free website optimization tool that dramatically reduces the file size of your images without any loss of quality.
Caire : Caire is a content aware image resize library