Affirm

The Affirm payment integration adds buy now, pay later financing directly to UltraCart checkout, letting shoppers split orders into four interest-free payments or longer monthly installment plans without leaving the store. Affirm handles the credit decision in real time, pays the merchant in full within one to three business days, and assumes all fraud and repayment risk.

Affirm was founded in 2012 by Max Levchin, a co-founder of PayPal, and has grown into a network of more than 337,000 merchants. The company built its brand on transparent financing with no late fees and no hidden charges, and Pay in 4 plans are always 0% APR for the consumer. Merchants on Affirm consistently report higher repeat purchase rates and meaningful AOV lift when the financing option is presented at checkout.

Most platforms hook into Affirm through a third-party app that adds a monthly fee and a separate checkout redirect that can drop conversion. UltraCart's Affirm integration is built directly into the checkout flow as an Advanced Payment method: paste the Affirm API Public Key and Private Key into the gateway configuration, choose Sandbox or Live, and Affirm renders inline alongside cards, PayPal, and wallets. Capture, refund, and partial refund all flow through Affirm's API automatically from the UltraCart order screen.

The integration works with any UltraCart Visual Builder theme (Elements, Hero, Jewel, Lifty, and Natural VB), supports both sandbox and production credentials side by side, and surfaces Affirm's monthly payment messaging on product and cart pages so shoppers see the financing offer before they reach checkout. Affirm is an asynchronous push-payment method, so it pairs best with standard one-time orders, multi-page checkout, and merchants who want to widen the audience for higher-ticket items.