We don't charge ATM withdrawal fees overseas (and, of course, we don't charge a fee for the card itself). We charge a flat currency conversion fee of 3.5% on the total transaction (no other fees). To see this fee and the exchange rate, tap on the transaction in the transaction list in the app, and it will show you the details.
Please be aware that some local banks MAY charge you for ATM withdrawals separately - this is not something we can control however :-( A couple of tips on avoiding unnecessary costs: 1) If the ATM or terminal ask which account you'd like to use, we suggest selecting 'credit' as this will most reliably allow the transaction to go through without extra fees. 2) If given the option, always choose to pay in the local currency. that way we'll be able to guarantee you a better exchange rate.