Callback for PG Load API

When a transaction is completed via the PG Load API, the result is communicated back to the merchant through a callback mechanism. The response parameters are sent to the surl (success URL) or furl (failure URL) that was provided in the original PG Load API request.

Callback Flow

Merchant initiates the load request using the PG Load API with mandatory fields like clientTxnId, surl, and furl
Customer completes the payment on the payment gateway page
Upon completion:
- PayU redirects the customer to the surl in case of success
- If the transaction fails, the customer is redirected to the furl
Callback parameters are sent to these URLs for final status tracking and reconciliation

Callback parameters

Parameter	Description	Example
merchantCode `mandatory`	`Numeric (10)` Merchant's unique ID provided by PayU for the load-money use case	180012
accosaTransactionId `mandatory`	`Numeric (10)` Unique Prepaid System transaction ID	3591893
responseCode `mandatory`	`Numeric (10)` Response code for transaction outcome (00 indicates success)	00
responseMessage `mandatory`	`Numeric (10)` Description of the response code	SUCCESS
clientTxnId `mandatory`	`Numeric (10)` Unique ID generated by the calling application	56894
txnAmount `optional`	`Numeric (10)` Original order amount in implied decimals	4100
loadAmount `mandatory`	`Numeric (10)` The actual amount loaded into the wallet	4100
accosaRefNo `mandatory`	`Numeric (10)` Auto-generated sequence number	424
status `mandatory`	`String` Transaction status (SUCCESS, FAILED)	SUCCESS
checksum `mandatory`	`String` Used for data integrity verification. You have to implement the following logic to calculate checksum to cross evaluate with one shared in surl/furl	900a98e04b4abc61 0bd0cb5623a470a4b0 d821d85551ae3baa410 11536cfe6b9

Sample callback response

When the transaction is completed, PayU sends the following parameters to your success or failure URL:

status=SUCCESS&AccosaRefNo=12321234&accosaTransactionId=1487&responseCode=00&responseMessage=Success&merchantCode=Vb007&clientTxnId=2023LOAD10000000003&txnAmount=1000&checksum=900a98e04b4abc610bd0cb5623a470a4b0d821d85551ae3baa41011536cfe6b9&loadAmount=4100

Checksum verification

To ensure the integrity of the callback data, a checksum is included in the callback parameters. The merchant should validate this checksum to confirm the authenticity of the response.

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Checksum logic: The checksum is calculated using the same algorithm and salt as used in the request hash calculation. You have to implement the following checksum logic:
ChecksumString: merchantCode|clientTxnId|loadAmount|accosaRefNo|accosaTransactionId|responseCode|responseMessage|merchantSalt 
 
Checksum: sha512(ChecksumString) 

Success and Failure Handling

Success scenario

When a transaction is successful:

The customer is redirected to the surl provided in the original request
The responseCode will be "00"
The status will be "SUCCESS"
The wallet will be credited with the amount specified in loadAmount

Failure scenario

When a transaction fails:

The customer is redirected to the furl provided in the original request
The responseCode will not be "00"
The status will be "FAILED"
An appropriate error message will be included in the responseMessage parameter