M-Pesa Express (STK push)

Sends a payment prompt to the customer's phone. The result is posted to callbackUrl; read it with parseStkCallback.

const sent = await mpesa.stkPush.send({
  shortCode: 174379,
  type: 'paybill',
  amount: 100,
  phoneNumber: '0712345678',
  callbackUrl: 'https://example.com/payments/stk',
  accountReference: 'INV-001',
  description: 'Invoice 001',
});

const status = await mpesa.stkPush.query({
  shortCode: 174379,
  checkoutRequestId: sent.checkoutRequestId,
});
if (status.resultCode === 0) console.log('paid');

stkPush.send:

Field	Daraja field	Notes
shortCode	BusinessShortCode	Paybill, or the HO/store number for till payments.
type	TransactionType	'paybill' (CustomerPayBillOnline) or 'till' (CustomerBuyGoodsOnline).
amount	Amount	Whole shillings, at least 1.
phoneNumber	PartyA, PhoneNumber	07…, 01…, +254… or 254….
partyB	PartyB	Optional. Defaults to shortCode; set it to the till number for tills.
callbackUrl	CallBackURL	Receives the result.
accountReference	AccountReference	Shown to the customer. 1 to 12 characters.
description	TransactionDesc	Optional. 1 to 13 characters; defaults to "Payment".

Password and Timestamp are generated from the configured passkey.

stkPush.query takes shortCode (BusinessShortCode) and checkoutRequestId (CheckoutRequestID), and returns resultCode (0 means paid; 1032 means the customer cancelled, 1037 that they didn't respond). Querying within about 30 seconds of the push can fail with 500.001.1001 "The transaction does not Exist"; retry later, or rely on the callback.