Photon (WordPress JetPack Plugin)
Jetpack is a popular modular plugin, adding loads of powerful functionality to WordPress websites. Since we’re talking about CDNs, we’ll be specifically looking at Jetpack’s Photon module. Photon isn’t a CDN, but it makes this list because it provides a WordPress-only image caching service through the Jetpack plugin. This means less load on your hosting server and faster images for your visitors.
There are a few limitations with this service. There are no cache invalidations, so currently the images are cached “forever” and if you want to refresh an image you will need to change the name of the image. Also, Photon only caches GIF, PNG and JPG files.
Pricing: Free product.