A free app for Android, by Transport for London TfL.
You can manage your Oyster card while on the go by adding it to this free Android app. Once you purchase a ticket or a Bus & Tram Pass, it will be readily accessible for pickup 30 minutes after purchase when you use your Oyster card at a yellow card reader while traveling on any London bus or at any Tube, DLR, London Overground, TfL Rail, or National Rail station.
This app will also ask for access to your camera so it can scan your credit card, but it won’t save the images that are taken.
If you did not know, the Oyster card is a contactless card that can be used for online purchases. As a result, you can use it to make payments on numerous websites, including Expedia and Amazon.