ASP.NET Web API Help Page

Introduction

This Payments API supports the Fiserv PaymentJS flow for card tokenization and payment. The typical sequence is: call AuthorizeSession to obtain a client token and public key; load the PaymentJS SDK and tokenize the card on the client; Fiserv POSTs the tokenization result to the Webhook endpoint; the client then calls ProcessTokenizedPayment to complete or continue the payment (including 3D Secure when required).

For 3D Secure: ThreeDSNotification receives the method form callback from Fiserv's ACS; ThreeDSComplete handles the challenge completion redirect (cRes). The TermUrl query uses MAC parameter termMac (legacy t); the method notification URL uses methodMac (legacy m; legacy sessions may still use bookingId and bookingHash on TermUrl until retired). If the ACS method notification is slow, the server sends EXPECTED_BUT_NOT_RECEIVED to Fiserv automatically while the client polls ProcessTokenizedPayment (see MethodNotReceivedTimeoutSeconds in fiserv.config)—there is no separate notify endpoint. ProcessTokenizedPayment has many possible response shapes (errors, still processing, already approved, 3DS challenge or method form, approved, failed, status). The API detail page for ProcessTokenizedPayment includes an "Additional information" section with the full list of response shapes.