By linking its installment lending service to Amazon, Affirm is gaining access to not only one of the largest e-commerce brands on the planet, but also a network of many smaller merchants that connect to Amazon’s payment and credit options. Amazon is testing Affirm’s buy now/pay later product with a limited number of consumers, with wider deployment expected down the road. It’s a major client win for Affirm, whose roster of about 12,000 merchants also includes major firms Walmart, Shopify and Peloton. Affirm could replace Amazon’s in-house financing option, and the partnership could be irksome to Amazon’s other payment partners, such as JPMorgan Chase, Visa and Synchrony Financial. And because companies like Affirm, Afterpay, Klarna and Sezzle encourage repeated use, they are akin to general-purpose payment systems.