Simon Willison’s Weblog

Are there any website thumbnail services that generate images in real-time?

My answer to Are there any website thumbnail services that generate images in real-time? on Quora

http://url2png.com/ generates images on demand—you pass the URL directly to the service and it replies with a PNG image. The first load can take a few seconds (depending on how long it takes the originating site to serve up the assets etc) but they cache the generated images so future requests for the same URL will be served instantly.