Yes they are. Flow uses Peach Payments as our secure payments provider. Peach is used by online stores you know and love.
Card payments are one of the safest ways to pay online as the process is fast and secure using end to end encryption technology. You can save a number of cards for convenience and select which one to use when you purchase your prepaid.
Peach Payments are compliant with all required security and regulatory protocols for handling cards online. Their website is here: https://www.peachpayments.com/.