Most major credit card companies offer price protection. Adding a Citibank, Mastercard card (from Barclays, Bank of America, First Premier, USBank or Capital One) or Visa into the Earny app is only important when it comes to Amazon purchases and extended your price protection.
Because Amazon doesn't have it's own price protection policy, you must use a price protected card in order to receive refunds on these items.
At all of our remaining retailers, you can pay with any type of credit card, debit card and even Paypal. No need to link any cards within the Earny app. Earny has you covered simply by making sure your electronic receipts are sent to your inbox because these retailers have a price protection policy of their own!