American Express is one of the largest credit card issuers in the United States. Along with Visa, Mastercard and Discover, they dominated the credit card issuer landscape.
There are 4 different ways to pay for American Express bill.
American Express Payment via letter:
American Express Payment Address
via American Express app: You can download the American Express app on Apple App Store or Google Android Play Store and make your payment directly on the app.
via Phone: Call American Express at 1-800-472-9297 or call the number on the back of your Amex credit card to make your payment
via online: Visit American Express and login with your username and password and make a payment online