Claire is a plug-in for Chrome or Firefox which will tell you which sites are using Cloudflare and also give you some useful diagnostic information for your own use. I admit I’m probably more tickled by it than most because I love it when I visit a random website to find someone is using our service.
But it’s also useful if you have multiple subdomains/hosts for confirming which are and are not proxying traffic through Cloudflare.
If you haven’t installed it yet, I encourage you to visit the Chrome store or the Mozilla Add-on section.
For the layperson, how does Claire help us diagnose our website other than displaying a basic dashboard indicating whether HTPP2, Railgun, and IPV6 are active? And why would you want to broadcast someone’s IP address and location? Isn’t that one of the main reasons for using CDN? (to hide origin IP and location). Very concerned about this plugin, information it collects, and the data it disseminates to hackers.
Knowing whether or not your site is actually routing through Cloudflare can be helpful (you’d be surprised at the number of support requests where Cloudflare “isn’t working” and the issue is either the domain isn’t orange clouded or the user has an alternate DNS or host fie config which is pointed somewhere other than where public DNS is.
Also knowing if you are using IPv4 vs. v6 can be useful in troubleshooting. There really shouldn’t be a reason that Ipv6 routing (or v4)shouldn’t work, but occasionally an ISP will break something and that can be a helpful troubleshooting exercise. But most useful is probably the Ray ID and the colo one is connecting to. If there appears to be a problem for users in a specific region or a specific Ray ID can be provided to support to look through our logs that can help to isolate/debug an issue.
The IP provided is the IP of our proxy, not the origin IP so no information is leaked (that can easily be determined using DNS). And the location is the POP the user is connecting to. Since we use an anycast network we broadcast the same IP address for a site proxied through Cloudflare from each of our POPs. Users will connect to the POP closest to them and knowing what POP that is can be useful for troubleshooting/debugging.
@philcloth there is a Firefox add-on available. I find the colors unintuitive (e.g. red means Cloudflare is active) but it does the job - though not as feature-rich as the Chrome extension. Not affiliated with this add-on.