A cloudflare developer (I think) has put a test site up here: https://filippo.io/Badfish/ https://filippo.io/Badfish/ The idea is something like <img src="

A cloudflare developer (I think) has put a test site up here: https://filippo.io/Badfish/ https://filippo.io/Badfish/ The idea is something like <img src="haveproblem.gif" onError="this.src='noproblem.gif'/> where haveproblem.gif is signed with the superfish cert (so you'll get an error if your machine does not have it, triggering the onError JS).