BudapestGO will not work below ground in the Budapest Metro! BudapestGO also does not prove an off-line verification of your validation of any ticket purchased in BudapestGO . So, even though you validate your tickets purchased in this app before getting on the Metro, when you get off, the “inspectors” will target tourists and demand to see your validation in BudapestGO , which will not show up. They will the demand 12,000 HUF ($35USD) in cash on the spot as a “fine.” It’s a scam and they know it. Good luck getting your money back. As soon as I turned a corner near an exit and got connection, boom! My validation appeared in BudapestGO . I went immediately back to the scammer/inspector, but she had fled. Her partner of course pretended not to know anything. Solutions. Do not reply on BudapestGO below ground in the Metro. I went to customer service and reported the incident and they are aware of the connection problems below ground. So you know these “inspectors “ know exactly where to stand and go after tourists. The money goes in their pocket and they disappear. Instead, use this app only above ground and if you have to use the Metro, purchase a separate, paper ticket and validate it through the machine so you have proof.