If you are flying internationally on a domestic carrier such as United or American Airlines, tracking an international flight is no different than tracking a domestic flight. This is also the case when flying on a code-share flight.  Yapta can track flights on a pre-purchase and post purchase basis for all supported domestic carriers. Airlines that Yapta supports

We have added the ability to track flights on some of the larger international carriers. Click here to view the complete list of Airlines tracked by Yapta. However, we only offer the ability to track flights from international carriers on a pre-purchase basis because most of them do not have any sort of Guaranteed Airfare policy that allows passengers to get a credid or voucher if the price of a ticket drops after it has been purchased.