How does Autoptimize and its Image Optimization + CDN service work?

Once you install Autoptimize on your website and turned on the Optimize Images settings located on Settings > Autoptimize > Images,

the URLs of your website's images will be changed to point to the ShortPixel CDN. For example, this image instead of being loaded from your host

will be optimized and resized on the fly, and then quickly loaded via CDN from a URL like this one:,h_400,q_lossy,ret_wait/

Unlike ShortPixel Image Optimizer, Autoptimize does not touch any of your files on your server; Autoptimize optimizes your images "on the fly". This is the detailed process, all transparent to users:

  1. A user loads a page containing images.
  2. While the page is loading, Autoptimize checks for any image URLs, for example:

  3. After detecting an image URL, it downloads that image to ShortPixel's servers, optimizes it and stores it on our CDN. This step is done only the first time an image is accessed.
  4. Then, Autoptimize replaces the URL with a new one, which points to our CDN containing the optimize image:

  5. Your page finishes loading and your images have been served from our fast CDN!

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