PromptPay

PromptPay is Thailand's national payment system that allows instant money transfers using phone numbers or national ID numbers.

Overview

PromptPay enables customers to pay instantly using their mobile banking app by scanning a QR code or entering a phone number/national ID.

Features

Instant Payments - Funds are transferred immediately
Wide Acceptance - Supported by all major Thai banks
No Fees - No transaction fees for customers
Secure - Uses bank-level security

Payment Flow

Create Payment - Merchant creates a payment with paymentMethod: 'promptpay'
Generate QR Code - One2Pays generates a QR code for the customer
Customer Scans - Customer scans QR code with their banking app
Payment Confirmed - Payment is confirmed instantly
Webhook Notification - Merchant receives webhook notification

Creating a PromptPay Payment

import crypto from 'crypto';

const API_KEY = process.env.PAYMENT_API_KEY!;
const API_SECRET = process.env.PAYMENT_API_SECRET!;

async function createPromptPayPayment() {
  const method = 'POST';
  const path = '/api/v1/payments';
  const body = JSON.stringify({
    amount: '1000.00',
    currency: 'THB',
    referenceId: 'order-12345',
    paymentMethod: 'promptpay',
    customerBankAccountName: 'John Doe',
    customerBankAccountNumber: '1234567890',
    customerBankCode: '004',
    description: 'Payment for order #12345',
  });
  const timestamp = Date.now().toString();

  const message = `${timestamp}.${body}`;
  const signature = crypto
    .createHmac('sha256', API_SECRET)
    .update(message)
    .digest('hex');

  const response = await fetch(`https://api.example.com${path}`, {
    method,
    headers: {
      'X-API-Key': API_KEY,
      'X-Timestamp': timestamp,
      'X-Signature': `sha256=${signature}`,
      'Content-Type': 'application/json',
    },
    body,
  });

  const result = await response.json();

  // Check nextAction to see if QR code/payment app URL is available
  if (result.data.nextAction?.type === 'use_payment_app') {
    // Redirect customer to payment page with QR code
    window.location.href = result.data.nextAction.paymentAppUrl;
  }
}

Payment Limits

Minimum: 1.00 THB
Maximum: 200,000 THB per transaction
Daily Limit: Varies by bank (typically 200,000 THB)

Processing Time

Instant - Payments are confirmed immediately
Webhook Delivery - Webhooks are sent within seconds of payment confirmation

Customer Experience

Customer sees QR code on payment page
Opens mobile banking app
Scans QR code or enters phone number
Confirms payment in banking app
Payment is confirmed instantly

Best Practices

Display QR Code Clearly - Ensure QR code is large and clear
Provide Instructions - Guide customers on how to use PromptPay
Handle Timeouts - PromptPay payments expire after a set time
Monitor Webhooks - Listen for payment status updates via webhooks

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