Old list:
https://cloudfour.com/thinks/image-resizing-services/
WordPress. Images uploaded to own server AND Cloudinary (via custom plugin). Markup is filtered to be a fancy srcset/sizes thing pointing to Cloudinary URLs.
(There are blog posts and screencasts about all this.)
Drew in Slack: "I’m pushing all my images to Azure storage, which then get served from Azure CDN"
Jenn: "We serve our images from Adobe Scene 7 and Contentful. Contentful does WebP conversion for us. In theory Scene 7 could too, but its a bit more convoluted"
CodePen: CodePen does a thing where Browserless takes screenshots, sends them to Kraken for optimization, then Kraken puts them in an S3 bucket. But Cloudfront sits in front of that. Any maybe Cloudflare in front of that?
CDNs
Screenshots