Payment21 is a digital lockbox that is designed to handle financial data originating from physical checks, ACH payments, and digital wallets. It can also work with payroll, bill pay, and credit card payments. The Payment21 API allows developers to include these alternative payment methods on their website. Several different integration methods are offered that vary in size and scope, including the Payment21 button, the simple API, the SOAP API, and shopping carts that already have Payment21 integrated.
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