PunyPNG : PunyPNG is a free website optimization tool that dramatically reduces the file size of your images without any loss of quality.
Crunch : Crunch is a tool for lossy PNG image file optimization. It combines selective bit depth, color type, and color palette reduction with zopfli DEFLATE c...
Squoosh : Squoosh is an image compression web app that allows you to dive into the advanced options provided by various image compressors.
RegPack : RegPack is a packer intended for use on minified Javascript code.
It is mostly suited to small size constraints (1kb, up to 4kb).
CSS Sprite Generator : This tool allows you to automate the process of generating CSS sprites. Simply give it a ZIP file containing 2 or more images (GIF, PNG or JPG) and it...
Trimage is a cross-platform GUI and command-line interface to optimize image files via optipng, pngcrush, advpng and jpegoptim