The Barclays app. HOW TO REGISTER If you're 16 or over and you have a UK-registered mobile number and a Barclays current account or Barclaycard, you. Got any questions about security? · Are you a Barclays customer? · The way you pay online is changing · Watch customers talking about the Barclaycard app. Barclays Mobile Banking App is an application available on Apple, Android and Windows devices for Barclays customers over the age of This app allows.