If you want to run your apps in localhost through IIS Express without having to launch Visual Studio in admin mode every time, run this one-time command through an admin-elevated cmd (replacing your app name and port):

>netsh http add urlacl url=http://localhost.myapp.com:1337/ user=everyone

Now you can launch Visual Studio in normal mode and when you Ctrl-F5, you won’t get a “failed to register url” error.