I’ve written before about cloud performance testing tools and how good they are - in fact they rank highly in my Five Essential Tools for Building REST APIs. Both loader.io and blitz.io use a similar mechanism to ensure that you own the domain you're about to load test. They generate a unique ID and ask you to put that in the root of your domain. Before any tests execute, they check that the file exists with the right content. It's a simple way of stopping people using the load test service to DDoS ......