UNAJIITA SHARP BOY
NA HUJUI KUPROMPT

Actors, money flow and architecture of a gateway. Set up your dev environment and project.

Create a Daraja app, use the sandbox, and fetch OAuth access tokens.

$r = http($base . '/oauth/v1/generate?grant_type=client_credentials',
  ['Authorization: Basic ' . base64_encode($key . ':' . $secret)]);
$token = $r['access_token'];

Build the request, password and timestamp, and trigger the PIN prompt on a phone.

$ts = date('YmdHis');
$body = [
  'BusinessShortCode' => $shortcode,
  'Password'  => base64_encode($shortcode . $passkey . $ts),
  'Timestamp' => $ts,
  'TransactionType' => 'CustomerPayBillOnline',
  'Amount' => 2000, 'PartyA' => $phone, 'PartyB' => $shortcode,
  'PhoneNumber' => $phone, 'CallBackURL' => $callbackUrl,
  'AccountReference' => 'ORDER42', 'TransactionDesc' => 'Payment',
];

Receive Safaricom callbacks, store receipts and update order status.

$cb = json_decode(file_get_contents('php://input'), true)['Body']['stkCallback'];
if ($cb['ResultCode'] === 0) {
    // mark the order as paid and store the M-Pesa receipt
}
echo '{"ResultCode":0,"ResultDesc":"Accepted"}';

Query transaction status, handle timeouts and cancellations, and avoid double charges.

Callback secrets, validation, logging and the Go Live checklist.

Build and deploy a working checkout page that collects money by STK Push.

Wallets, networks, gas fees and testnets. How a crypto payment is confirmed.

Create orders, show payment details and wait for confirmations.

Write and deploy a simple payment contract that emits an event for every payment.

event Paid(address indexed payer, uint256 orderId, uint256 amount);

function pay(uint256 orderId) external payable {
    require(msg.value > 0, "No payment");
    emit Paid(msg.sender, orderId, msg.value);
}

Connect a wallet and send a payment from your web app with ethers.js.

const provider = new ethers.BrowserProvider(window.ethereum);
const signer = await provider.getSigner();
const tx = await signer.sendTransaction({
  to: SHOP_ADDRESS, value: ethers.parseEther("0.01")
});
await tx.wait(); // payment confirmed on-chain

Watch blockchain events and match each payment to the right order.

contract.on("Paid", (payer, orderId, amount) => {
  markOrderPaid(orderId, payer, amount); // match on-chain payment to your order
});

Combine M-Pesa and crypto, then handle refunds and reconciliation.

Demo your gateway, deploy it and get feedback.