It is very easy to top up. You can do this at:
- Tube, DLR, London Overground, TfL rail, and most National Rail stations.
- Over 4000 local shops in London called Oyster Ticket Stops.
- Transport for London Visitor Centres.
You will see what look like ATM machines which have the yellow Oyster Card symbol on them. You will need to tap the card and then follow the machine’s prompts to top it up.