M-Pesa Express (STK Push)

Merchant-initiated C2B payment. Sends a USSD payment prompt to the customer's phone.

Initiate STK Push

var mpesaExpress = new MpesaExpress(gateway, passKey);

var payload = new MpesaExpressPayload
{
    BusinessShortCode = 174379,
    Passkey = passKey,
    TransactionType = TransactionType.CustomerPayBillOnline,
    Amount = 1,
    PartyA = "254708374149",
    PartyB = "174379",
    PhoneNumber = "254708374149",
    CallBackURL = "https://mydomain.com/callback",
    AccountReference = "MyApp",
    TransactionDesc = "Payment"
};

var result = await mpesaExpress.InitiateStkPush(payload);

if (result.IsSuccess)
{
    Console.WriteLine($"CheckoutRequestID: {result.Value!.CheckoutRequestID}");
}

Payload Properties

Property	Type	Required	Description
`BusinessShortCode`	`int`	Yes	Paybill or Till number
`Passkey`	`string`	Yes	Passkey from the Daraja portal
`TransactionType`	`TransactionType`	Yes	`CustomerPayBillOnline` (Paybill) or `CustomerBuyGoodsOnline` (Till)
`Amount`	`decimal`	Yes	Transaction amount
`PartyA`	`string`	Yes	Phone number sending money (`2547XXXXXXXX`)
`PartyB`	`string`	Yes	Organization receiving funds
`PhoneNumber`	`string`	Yes	Phone number to receive the USSD prompt (`2547XXXXXXXX`)
`CallBackURL`	`string`	Yes	URL for payment result notification
`AccountReference`	`string`	Yes	Identifier shown to customer (max 12 chars)
`TransactionDesc`	`string`	No	Additional info (max 13 chars)

Password and Timestamp are set automatically by the SDK.

Query Transaction Status

var queryResult = await mpesaExpress.QueryStkPushStatus(
    businessShortCode: 174379,
    checkoutRequestId: result.Value!.CheckoutRequestID
);

if (queryResult.IsSuccess)
{
    Console.WriteLine($"ResultCode: {queryResult.Value!.ResultCode}");
    Console.WriteLine($"ResultDesc: {queryResult.Value.ResultDesc}");
}

Response Properties

STK Push Response

Property	Description
`MerchantRequestID`	Unique ID from the API proxy
`CheckoutRequestID`	Unique ID from M-PESA
`ResponseCode`	`0` = successful submission
`ResponseDescription`	Submission status message
`CustomerMessage`	Message for the customer

Query Response

Property	Description
`ResponseCode`	`0` = successful submission
`ResponseDescription`	Submission status message
`MerchantRequestID`	Unique ID from the API proxy
`CheckoutRequestID`	Unique ID from M-PESA
`ResultCode`	`0` = successful processing
`ResultDesc`	Processing result message