This might be obvious, but if you don’t want to have a test server online because Facebook doesn’t seem to allow “localhost”, all you need to do is edit your hosts file.
Yep, it’s THAT simple. Here are the locations of the hosts file on different systems.
All you need to do is add an entry:
This should only be used for the very first stages of your site development, as it doesn’t allow any other users. It also might not be team-friendly. In that case, you can use a dynamic DNS service and use a temporary URL in the App’s settings.
Note: It’s possible that if you’re behind a router and you use a dynamic DNS service, *you* will be shown your router’s control panel. Confirm this with a trusted friend before giving away the temporary URL. Once you’re sure only you can see your router’s control panel, correct this issue locally by using the hosts file solution above.