Pilbox looks great. Added it to this list of such image resizing services:

  https://github.com/adamdbradley/foresight.js/wiki/Server-Resizing-Images

Many, many implementations, and each goes about it differently. There's unfortunately no widely adopted standard for constructing a URL to request a resized/altered image.

It would be great to see traction on something like this RESTful Image API Specification:

  https://github.com/riapi/riapi