Thumbor is an open-source, on-demand image service which allows for server-side cropping, resizing, and compositing of images. Rather than downloading a large image and scaling it to fit the display, the image is requested at the exact desired size and the server does the work on-demand to resize it before delivering. Using Thumbor has alleviated the burden of dealing with images of all different sizes in our clients while also allowing them to operate much more efficiently.