Doing a server migration and attempting to test the new server before updating the DNS. I was hoping this would work (I'm using the latest Waterfox 56) though even after properly setting the IP, domain and even restarting the browser outright my website which shows the server IP address in Administrator mode was still pulling the old IP address. Maybe I missed something? Will try another extension. If the author replies with something useful I'd be willing to try again.

Does not work with HTTPS sites. Does not appear that "Host" header is properly formatted with the desired host. Not easy to copy and paste two values into the fields {host, address}. One of them has to be entered manually

This addon would be useful if it wasn't for the fact that as soon as I switch window to copy the IP or hostname of a server, the addon closes, thus clearing the values I entered. Essentially, you are not going to be able to copy and paste both the IP and hostname in to the plugin, you will have to type one. This is pretty poor design but something which can probably be fixed easily. I hope they fix it so I can actually use this. Until then, I will be uninstalling.

Bohužel to nefunguje jako WIn hosts. Akorát mi to přepíše na danou IP, ale komunikace už nic moc. Škoda, čekal jsem více...

Didn't think it was working at first but it is. New IPs weren't being used until I tried visiting the site in a private window, guess a cache needs to be cleared at first or something?

Easy to use and seems to work as intended... so, good job :)