CloudFlare has a bunch of error pages that are shown to web users depending upon the problem at any given them.
Free account users have been able to make some changes to their CloudFlare Challenge Page.
CloudFlare has now rolled out features that allow paying subscribers to make more changes to these error pages.
The ability to customize all of the error pages CloudFlare generates is restricted to paid CloudFlare plans. The only exception to this rule is that all domains, regardless of pricing plan, can make basic changes to their CloudFlare challenge page.
Read more about these changes here .