When reading the subdomain of an xip.io request, you will get a different value compared to a local pow request. The reason for this is that the tld length is 1 by default, but an xip.io request has a tld length of 6. This gem inserts a middleware that corrects the tld length config of rails on the fly so that you can use local and xip requests at the same time without restarting the server.