We have a list of countries where the cards do not work - these are displayed in the terms and conditions during the Visa and Mastercard checkout flow (that is, just scroll down after clicking on the Visa or Mastercard product).

In terms of Europe, our Visa cards are hit-or-miss due to many merchants requiring 3DS enabled cards (which these are not, due to not having a name or address associated with them). Our prepaid Visa cards tend to work well in Croatia and Germany, and often times at larger merchants (like McDonald’s) for small value transactions (< 30 EUR). However, we've had intermittent issues reported in other countries in the EU.

On the other hand, our EUR-loaded Mastercards are 3DS enabled and should work with EU merchants requiring 3DS cards.

Usually the best strategy is to purchase a relatively low value card for testing purposes (eg, less than $10). If it works with the retailer you're intending to use it with, then you can scale up your purchases from there.