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How does Autoptimize and its Image Optimization service work?

If you turn on the setting “Optimize Images” (located on Settings > Autoptimize > Images), Autoptimize will analyze the code of your web pages every time a user visits them and it will replace each original unoptimized image with the optimized image. Each replaced image is served from the ShortPixel CDN

Notice that Autoptimize does not touch any of your files, their URL or their metadata on your server; Autoptimize optimizes your images on-the-fly, when one of your pages is loaded by a visitor, which means that if you want to “return” to your original images, you can simply disable the option “Optimize Images”. This is the detailed process, completely transparent to all users:

  1. A user visits a page containing images.
  2. While the page is loading, Autoptimize checks for any image URLs on the code of the page. For example:

  3. After detecting an image URL, it sends that image to ShortPixel’s optimization servers, which optimize it and store it on ShortPixel’s CDN. This step is done only the first time a specific image is viewed or requested from one your visitors when the page loads.
  4. Autoptimize then replaces the original URL with a new one, which points to our CDN containing the optimized image:

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