Transloadit can resize, crop, and (auto-)rotate images, as well as watermark them or read & write meta-data.
The /image/optimize Robot reduces the size of images while maintaining the same visual quality.
The /image/optimize Robot's Parameters
Interlaces the image if set to true, which makes the result image load progressively in browsers. Instead of rendering the image from top to bottom, the browser will first show a low-res blurry version of the image which is then quickly replaced with the actual image as the data arrives. This greatly increases the user experience, but comes at a loss of about 10% of the file size reduction.
Specifies if the image's meta data should be preserved during the optimization, or not. If it is not preserved, the file size is even further reduced. This option is mandatory if you set png_tool to "pngquant"
If set to true this parameter tries to fix images that would otherwise make the underlying tool error out and thereby break your Assemblies. This can sometimes result in a larger file size, though.