Authorize Transaction

post

https://sandbox.affirm.com/api/v1/transactions

Authorizes a transaction. After a user completes the Affirm checkout flow and returns to the merchant site, the merchant should call the Authorize Transaction endpoint. Authorizing a transaction generates a unique id that will be used as a reference moving forward.

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New Required Fields
The new required fields are the following:

currency: Three-letter ISO currency code in uppercase. Accepted currencies are USD, CAD, and GBP.

items: Various details of the item being sold.

shipping: The shipping details.

total: The total amount of the checkout in the lowest denomination of the currency. (e.g., 100 cents to charge $1.00).

Body Params

The request body used to create a transaction.

expand

string

A comma-separated set of related objects to expand in the response.

order_id

string

length between 1 and 128

Identifies the order within the merchant's order management system that this transaction corresponds to. It is only returned in the response if included in the request.

reference_id

string

length between 1 and 128

An optional, unique identifier that may be associated with each transaction event and reconciled with the system of record used by the merchant.

transaction_id

string

length between 9 and 16

Required. A unique identifier representing the checkout.

currency

string

Three-letter ISO currency code in uppercase.

total

integer

The total amount of the checkout in the lowest denomination of the currency.

shipping

object

items

array of objects

An array of various details of the item being sold.

items

Headers

Idempotency-Key

string

Unique identifier pre-generated by the client and used by the server to recognize successive calls to the same endpoint. This is required for Split Capture and encouraged for single transaction functionality. Note: If a request fails or times out, use the same idempotency key to retry the operation without risk of double-processing. For details, see the Idempotency section on About Split Capture.

Responses

200HTTP 200 OK

400HTTP 400 Bad Request

401HTTP 401 Unauthorized

404HTTP 404 Not Found