Only the official marketplace can validate the barcodes. For example, Ticketexchange for most pro sports other than baseball and StubHub for most major league baseball teams.<p>An individual can do an ad hoc validation of a given ticket by trying to create a listing on the official marketplace. You will be able to create a listing <i>only</i> if the ticket is valid <i>and</i> unencumbered (by an existing resale listing).