Open API >Online Payments >UnionPay SRC API (SRCi-Merchant)
UnionPay SRC API (SRCi-Merchant)
Online Payments Merchant
The API is the introduction document of the interface between merchants and UnionPay SRCi.
API Introduction
API Introduction
What is it?

The API provides a basic introduction of UnionPay SRC (Click to Pay) business as well as the transaction processing and messages of the interfaces between merchants and UnionPay SRCi.

Key Features

Frictionless checkout flow

Improved user experience

EMVCo standard compliance

No PCI pressure

Support 3rd party wallet (DCF)

When to Use it?

Merchants can initiate SRC checkout flow via this API when consumers select Union Pay SRC (Click to Pay) to pay.

Who Use it?
Where to Use it?
Global Markets
Flow Chart
Flow Chart


API Reference
API Reference
  • SRC Checkout
  • Checkout Result Notification
  • Merchant Get Payload
  • Checkout Event Result Notification
Interface description
After the consumer selects Click to Pay on the Merchant’s website, the Merchant sends UPSRC_CHECKOUT request to UPI SRCi. UPI SRCi processes the request and returns the HTTP response with the response body being NULL.
Request Method
Request Parameter
Field name Identifier Type Length Request Default value Note
Message ID msgID AN 44 M:Mandatory It is used to match a response to its request. The value must uniquely identify any message that the institution initiates on any day. Format: “S”+ Merchant ID + Acquirer IIN + Transmission Date and Time (YYYYMMDDhhmmss) + System Trace Audit Number (6 numeric digits). Note 1: Merchant ID in “msgID” is of 15 bytes. If “merchantID” is less than 15 bytes, it is right-padded with spaces in “msgID”. Note 2: Transmission Date and Time shall be filled by Beijing time (UTC+8).
Transaction Type transactionType ANS 1-30 M:Mandatory Type of transaction initiated for which the SRC Checkout request is sent. Filled with “PURCHASE” by default.
Local Transaction Date &Time localTxnDateTime N 10 M:Mandatory Format: MMDDhhmmss
Acquirer IIN acquirerIIN AN 8 M:Mandatory The unique value assigned by UPI to uniquely identify the Acquirer.
Merchant ID merchantID ANS 1-15 M:Mandatory The unique value assigned by the Acquirer to uniquely identify the Merchant within the Acquirer’s system.
Merchant Category Code mcc N 4 M:Mandatory A 4-digit numeric value, as defined by [UPI OR], indicates the merchant type.
Merchant Country Code merchantCountry N 3 M:Mandatory A 3-digit numeric value
Merchant Name merchantName ANS 1-25 M:Mandatory
Merchant Abbreviation merchantAbbr ANS 1-8 M:Mandatory
Secondary Merchant ID subMerchantID AN 5-25 C:Conditional It is filled when the Merchant is a Platform Merchant.
Secondary Merchant Name subMerchantName ANS 1-40 C:Conditional It is filled when the Merchant is a Platform Merchant.
3DS Preference threeDsPreference ANS 1-20 O:Optional Merchant’s 3DS preferences. Valid values: “NONE”, which indicates 3DS is not to be performed. “SELF”, which indicates 3DS is to be performed by the Merchant itself. The default value is “NONE” if the field is not submitted.
Transaction Amount trxAmt ANS 1-13 M:Mandatory The value shall only include (numeric) digits "0" to "9" and may contain a single "." character as the decimal mark. When the amount includes decimals, the "." character shall be used to separate the decimals from the integer value, and the "." character may be present even if there are no decimals.
Transaction Currency trxCurrency N 3 M:Mandatory A 3-digit numeric value, as defined in Technical Specifications on Bankcard Interoperability – Part VI Annex in line with ISO 4217, indicates the currency code of the transaction. The mobile application can display the transaction currency in a readable way, such as "RMB".
Payload Type for Checkout payloadTypeIndicatorCheckout ANS 1-20 M:Mandatory Valid Values: “SUMMARY”, which indicates payload is not to be returned in CHECKOUT_RESULT_NOTIFICATION. “PAYMENT”, which indicates payment payload is to be returned in CHECKOUT_RESULT_NOTIFICATION
Merchant Back-end URL backUrl ANS 1-256 O:Optional The URL is used by the Merchant backend to receive the checkout result in CHECKOUT_RESULT_NOTIFICATION interface.
JWS Signature signature ANS 1-2048 M:Mandatory Filled with the value of UPI-JWS signature, which is calculated in line with Section 5.2 JWS Signature in UPI Server-based API General Requirements. PLEASE NOTE that the JWS Payload is the entity body of HTTP message excluding the “signature” data field.
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