NEW YORK (MainStreet) —American Express (Stock Quote: AXP) announced Monday a new digital payment platform that will allow consumers to pay for purchases with more than just an Amex-branded credit card.

The new platform, called Serve, lets users make purchases online or via mobile phone with merchants that accept American Express cards. Serve accounts can be funded by bank accounts, debit cards, credit and charge cards or other Serve accounts, and customers can use those accounts to send and receive money to friends, pay bills and make purchases online.

Additionally, each customer will be issued a reloadable prepaid card linked to his Serve account that can be used at any merchant or ATM that accepts American Express cards. A spokesperson for American Express confirmed you don’t need to be an Amex cardholder to set up an account.

“Serve is a new type of payment platform that isn’t tied to a single card or mobile operating system. It’s a flexible, easy-to-use platform, which from day one brings tremendous assets to the alternative payments space and gives consumers an option to shop online and offline at millions of merchants who accept American Express,” Dan Schulman, group president, Enterprise Growth, American Express, said in a written statement.

American Express will waive all fees associated with the service for the next six months, but after that, loading money onto the account from a credit card will cost 2.9% of the amount, plus 30 cents. Loading funds through cash, debit or ACH (automated clearing house) transactions will be free.

ATM cash withdrawals using the Serve card will cost $2, though the first withdrawal each month will be free. Serve does not charge for person-to-person payments made between, but will impose a fee of 2.9% of the transaction amount, plus 30 cents on person-to-person payments made for goods and services. (For instance, a small online merchant selling jewelry from his or her home would be charged the fee to accept a P2P payment from a customer.)

The move marks the company’s first foray into the growing mobile payment market, a platform we previously reported is estimated to generate $214 billion worth of transactions in the U.S. by 2015.

It follows a somewhat similar move by Visa (Stock Quote: V) , which launched its own person-to-person payment program last week that makes it possible for consumers to transfer money to one another without having to rely on cash, checks or services like PayPal.

“Consumers are clearly transitioning toward digital payments,” David Messenger, executive vice president and head of the online and mobile business unit of American Express, told MainStreet. “Clearly, this represents a huge growth opportunity moving forward and that’s why we are launching now.”

Messenger said that American Express will add new features and functionality to the service in the future, based on how consumers use the service and what partners it is able to enlist moving forward, though he did not specify what those features would entail. Three of the company’s first partners are Ticketmaster, Concur and Flipswap, an eco-conscious retail trade-in website.

U.S. customers can currently set up an online account at Serve.com or via smartphone; the mobile app is currently available for iPhones or Android-enabled phones.

Messenger said the service will launch internationally within the next year.

—For the best rates on loans, bank accounts and credit cards, enter your ZIP code at BankingMyWay.com.