SAN FRANCISCO (AP) — Amazon is teaming with payments company Affirm to offer online shoppers a buy-now-pay-later option that does not involve credit cards. San Francisco-based Affirm Holdings Inc. announced Friday that it’s flexible payment service will soon be available on Amazon.com. The news sent Affirm’s stock up more than 35% in after-hours trading. With the service, Amazon customers can split the total cost of purchases of $50 or more into monthly payments, and are told the total cost of the transaction up front. Affirm said the two companies are testing the service with a group of customers and it will be more broadly available in coming months.