Ever wondered why you can't get past the ticket barriers with your Oyster, Contactless card, Oyster, smartcard or standard ticket? Just have a look at the code that pops up on the barrier and check it on our app. Our app supports the Oyster Card, contactless credit/debit cards, standard magnetic tickets, and ITSO Smartcards (like The Key). The error codes in our app match both TfL and National Rail's error code list, meaning you can be sure that you're getting correct and up-to-date information