When you use your password and email to log in to your Mynt account, the system will ask you to use a secure login method when you want to view sensitive information such as card numbers and PIN codes.

Once logged into the Mynt app, you can perform a secure login by going to "cards", click on a card and "show card details":
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And "send code":
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A one-time code will now be sent by sms to your phone number.

Enter the code to view the card information in the app.