Step 3: Send the Customer to Payfast for Payment

Your form should POST to either:

Live: https://www.payfast.co.za/eng/process
Sandbox (Testing): https://sandbox.payfast.co.za/eng/process

Full PHP Form Implementation

<?php
// Construct variables
$cartTotal  = 10.00; // Source this from your application
$passphrase = 'jt7NOE43FZPn';

$data = array(
    // Merchant details
    'merchant_id'    => '10000100',
    'merchant_key'   => '46f0cd694581a',
    'return_url'     => 'http://www.yourdomain.co.za/return.php',
    'cancel_url'     => 'http://www.yourdomain.co.za/cancel.php',
    'notify_url'     => 'http://www.yourdomain.co.za/notify.php',

    // Buyer details
    'name_first'     => 'First Name',
    'name_last'      => 'Last Name',
    'email_address'  => 'test@test.com',

    // Transaction details
    'm_payment_id'   => '1234', // Unique payment ID for notify_url
    'amount'         => number_format(sprintf('%.2f', $cartTotal), 2, '.', ''),
    'item_name'      => 'Order#123'
);

// Generate signature (see Step 2)
$signature        = generateSignature($data, $passphrase);
$data['signature'] = $signature;

// Determine environment
$testingMode = true;
$pfHost      = $testingMode ? 'sandbox.payfast.co.za' : 'www.payfast.co.za';

// Build the HTML form
$htmlForm = '<form action="https://'.$pfHost.'/eng/process" method="post">';
foreach ($data as $name => $value) {
    $htmlForm .= '<input type="hidden" name="'.$name.'" value=\''.$value.'\' />';
}
$htmlForm .= '<input type="submit" value="Pay Now" /></form>';

// Output form
echo $htmlForm;
?>

const myData = [];
// Merchant details
myData["merchant_id"] = "10000100";
myData["merchant_key"] = "46f0cd694581a";
myData["return_url"] = "http://www.yourdomain.co.za/return_url";
myData["cancel_url"] = "http://www.yourdomain.co.za/cancel_url";
myData["notify_url"] = "http://www.yourdomain.co.za/notify_url";
// Buyer details
myData["name_first"] = "First Name";
myData["name_last"] = "Last Name";
myData["email_address"] = "test@test.com";
// Transaction details
myData["m_payment_id"] = "1234";
myData["amount"] = "10.00";
myData["item_name"] = "Order#123";

// Generate signature
const myPassphrase = "jt7NOE43FZPn";
myData["signature"] = generateSignature(myData, myPassphrase);

let htmlForm = `<form action="https://${pfHost}/eng/process" method="post">`;
for (let key in myData) {
  if(myData.hasOwnProperty(key)){
    value = myData[key];
    if (value !== "") {
      htmlForm +=`<input name="${key}" type="hidden" value="${value.trim()}" />`;
    }
  }
}

htmlForm += '<input type="submit" value="Pay Now" /></form>';

data = {
    # Merchant details
    'merchant_id': '10000100',
    'merchant_key': '46f0cd694581a',
    'return_url': 'http://www.yourdomain.co.za/return.php',
    'cancel_url': 'http://www.yourdomain.co.za/cancel.php',
    'notify_url': 'http://www.yourdomain.co.za/notify.php',
    # Buyer details
    'name_first': 'First Name',
    'name_last': 'Last Name',
    'email_address': 'test@test.com',
    # Transaction details
    'm_payment_id': '1234', #Unique payment ID to pass through to notify_url
    'amount': "200",
    'item_name': 'Order#123'
}

# Generate signature (see step 2)
passphase = 'jt7NOE43FZPn';
signature = generateSignature(data, passphase);
data['signature'] = signature;

# If in testing mode make use of either sandbox.payfast.co.za or www.payfast.co.za
SANDBOX_MODE = True;
pfHost = 'sandbox.payfast.co.za' if SANDBOX_MODE else 'www.payfast.co.za'


htmlForm = f'<form action="https://{pfHost}/eng/process" method="post">'
for key in data:
    htmlForm += f'<input name="{key}" type="hidden" value="{data[key]}" />'

htmlForm += '<input type="submit" value="Pay Now" /></form>'