qpay-js

TypeScript/JavaScript client library for the QPay V2 payment API. Works in Node.js (18+) and modern browsers.

Installation

npm install qpay-js

Quick Start

import { QPayClient, loadConfigFromEnv } from 'qpay-js';

// Load config from environment variables
const config = loadConfigFromEnv();
const client = new QPayClient(config);

// Create an invoice
const invoice = await client.createSimpleInvoice({
  invoiceCode: 'TEST_INVOICE',
  senderInvoiceNo: 'ORDER-001',
  invoiceReceiverCode: 'terminal',
  invoiceDescription: 'Payment for Order #001',
  amount: 10000,
  callbackUrl: 'https://example.com/api/qpay/callback',
});

console.log(invoice.invoiceId);    // "abc123..."
console.log(invoice.qPayShortUrl); // "https://qpay.mn/s/..."
console.log(invoice.qrImage);      // base64-encoded QR image

Configuration

From environment variables

Set the following environment variables, then call loadConfigFromEnv():

Variable	Description
QPAY_BASE_URL	QPay API base URL (e.g., https://merchant.qpay.mn)
QPAY_USERNAME	QPay merchant username
QPAY_PASSWORD	QPay merchant password
QPAY_INVOICE_CODE	Default invoice code
QPAY_CALLBACK_URL	Payment callback URL

import { QPayClient, loadConfigFromEnv } from 'qpay-js';

const client = new QPayClient(loadConfigFromEnv());

Manual configuration

import { QPayClient } from 'qpay-js';
import type { QPayConfig } from 'qpay-js';

const config: QPayConfig = {
  baseUrl: 'https://merchant.qpay.mn',
  username: 'YOUR_USERNAME',
  password: 'YOUR_PASSWORD',
  invoiceCode: 'YOUR_INVOICE_CODE',
  callbackUrl: 'https://example.com/api/qpay/callback',
};

const client = new QPayClient(config);

Usage

Authentication

The client manages tokens automatically. When you call any API method, it will obtain a token if needed, refresh it when it expires, and re-authenticate if the refresh token also expires.

You can also manage tokens manually:

// Get a new token pair
const token = await client.getToken();
console.log(token.accessToken);
console.log(token.refreshToken);
console.log(token.expiresIn);

// Refresh the current token
const refreshed = await client.refreshToken();

Create Invoice

Full invoice with all options:

const invoice = await client.createInvoice({
  invoiceCode: 'TEST_INVOICE',
  senderInvoiceNo: 'ORDER-001',
  invoiceReceiverCode: 'terminal',
  invoiceDescription: 'Payment for Order #001',
  amount: 50000,
  callbackUrl: 'https://example.com/api/qpay/callback',
  senderBranchCode: 'BRANCH01',
  enableExpiry: 'true',
  allowPartial: false,
  minimumAmount: 1000,
  allowExceed: false,
  maximumAmount: 100000,
  note: 'Special order',
  lines: [
    {
      lineDescription: 'Product A',
      lineQuantity: '2',
      lineUnitPrice: '25000',
      taxes: [{ description: 'VAT', amount: 2500 }],
    },
  ],
});

console.log(invoice.invoiceId);
console.log(invoice.qrText);
console.log(invoice.qrImage);
console.log(invoice.qPayShortUrl);

// Deep links for mobile banking apps
for (const url of invoice.urls) {
  console.log(`${url.name}: ${url.link}`);
}

Create Simple Invoice

Minimal fields for quick invoice creation:

const invoice = await client.createSimpleInvoice({
  invoiceCode: 'TEST_INVOICE',
  senderInvoiceNo: 'ORDER-002',
  invoiceReceiverCode: 'terminal',
  invoiceDescription: 'Quick payment',
  amount: 10000,
  callbackUrl: 'https://example.com/api/qpay/callback',
});

Create Ebarimt Invoice

Invoice with tax (ebarimt) information:

const invoice = await client.createEbarimtInvoice({
  invoiceCode: 'TEST_INVOICE',
  senderInvoiceNo: 'ORDER-003',
  invoiceReceiverCode: 'terminal',
  invoiceDescription: 'Taxed payment',
  taxType: 'CITIZEN',
  districtCode: 'UB',
  callbackUrl: 'https://example.com/api/qpay/callback',
  lines: [
    {
      lineDescription: 'Service fee',
      lineQuantity: '1',
      lineUnitPrice: '30000',
      taxProductCode: 'TAX001',
    },
  ],
});

Cancel Invoice

await client.cancelInvoice('INVOICE_ID');

Get Payment

const payment = await client.getPayment('PAYMENT_ID');

console.log(payment.paymentId);
console.log(payment.paymentStatus);  // "PAID", "PENDING", etc.
console.log(payment.paymentAmount);
console.log(payment.paymentCurrency);
console.log(payment.paymentDate);
console.log(payment.transactionType);

Check Payment

Check if a payment has been made for an invoice:

const result = await client.checkPayment({
  objectType: 'INVOICE',
  objectId: 'INVOICE_ID',
  offset: { pageNumber: 1, pageLimit: 10 },
});

console.log(result.count);
console.log(result.paidAmount);

for (const row of result.rows) {
  console.log(row.paymentId, row.paymentStatus, row.paymentAmount);
}

List Payments

const result = await client.listPayments({
  objectType: 'INVOICE',
  objectId: 'INVOICE_ID',
  startDate: '2026-01-01',
  endDate: '2026-12-31',
  offset: { pageNumber: 1, pageLimit: 20 },
});

for (const item of result.rows) {
  console.log(item.paymentId, item.paymentDate, item.paymentAmount);
}

Cancel Payment

Cancel a card payment:

await client.cancelPayment('PAYMENT_ID', {
  callbackUrl: 'https://example.com/api/qpay/cancel-callback',
  note: 'Customer requested cancellation',
});

// Or without options
await client.cancelPayment('PAYMENT_ID');

Refund Payment

Refund a card payment:

await client.refundPayment('PAYMENT_ID', {
  callbackUrl: 'https://example.com/api/qpay/refund-callback',
  note: 'Refund for returned item',
});

// Or without options
await client.refundPayment('PAYMENT_ID');

Create Ebarimt

Create an electronic tax receipt for a payment:

const ebarimt = await client.createEbarimt({
  paymentId: 'PAYMENT_ID',
  ebarimtReceiverType: 'CITIZEN',
  districtCode: 'UB',
});

console.log(ebarimt.id);
console.log(ebarimt.ebarimtQrData);
console.log(ebarimt.ebarimtLottery);
console.log(ebarimt.amount);
console.log(ebarimt.vatAmount);

Cancel Ebarimt

const cancelled = await client.cancelEbarimt('PAYMENT_ID');
console.log(cancelled.barimtStatus); // "CANCELLED"

Error Handling

All API errors throw a QPayError with structured information:

import { QPayError, isQPayError, ERR_INVOICE_NOT_FOUND } from 'qpay-js';

try {
  await client.getPayment('NONEXISTENT');
} catch (err) {
  if (isQPayError(err)) {
    console.log(err.statusCode); // 404
    console.log(err.code);       // "INVOICE_NOTFOUND"
    console.log(err.message);    // "qpay: INVOICE_NOTFOUND - Invoice not found (status 404)"
    console.log(err.rawBody);    // Raw JSON response body

    // Compare against known error codes
    if (err.code === ERR_INVOICE_NOT_FOUND) {
      // Handle specific error
    }
  }
}

Available Error Code Constants

The library exports all QPay error codes as constants:

import {
  ERR_AUTHENTICATION_FAILED,
  ERR_INVOICE_NOT_FOUND,
  ERR_INVOICE_PAID,
  ERR_INVOICE_ALREADY_CANCELED,
  ERR_PAYMENT_NOT_FOUND,
  ERR_PAYMENT_NOT_PAID,
  ERR_PAYMENT_ALREADY_CANCELED,
  ERR_PERMISSION_DENIED,
  ERR_INVALID_AMOUNT,
  ERR_MERCHANT_NOT_FOUND,
  ERR_MERCHANT_INACTIVE,
  // ... and more
} from 'qpay-js';

Browser Usage

This library works in modern browsers that support the fetch API. No polyfills are needed for current browsers.

<script type="module">
  import { QPayClient } from 'qpay-js';

  const client = new QPayClient({
    baseUrl: 'https://merchant.qpay.mn',
    username: 'YOUR_USERNAME',
    password: 'YOUR_PASSWORD',
    invoiceCode: 'YOUR_INVOICE_CODE',
    callbackUrl: 'https://example.com/callback',
  });

  const invoice = await client.createSimpleInvoice({
    invoiceCode: 'TEST',
    senderInvoiceNo: 'ORDER-001',
    invoiceReceiverCode: 'terminal',
    invoiceDescription: 'Browser payment',
    amount: 5000,
    callbackUrl: 'https://example.com/callback',
  });

  // Display QR code
  document.getElementById('qr').src = `data:image/png;base64,${invoice.qrImage}`;
</script>

Note: In browser environments, loadConfigFromEnv() will not work because process.env is not available. Use manual configuration instead.

API Reference

QPayClient

Method	Description
new QPayClient(config)	Create a new client with the given config
getToken()	Authenticate and return a token pair
refreshToken()	Refresh the current access token
createInvoice(req)	Create a detailed invoice
createSimpleInvoice(req)	Create a simple invoice with minimal fields
createEbarimtInvoice(req)	Create an invoice with ebarimt (tax) data
cancelInvoice(invoiceId)	Cancel an invoice by ID
getPayment(paymentId)	Get payment details by ID
checkPayment(req)	Check if a payment has been made
listPayments(req)	List payments with filters
cancelPayment(paymentId, req?)	Cancel a card payment
refundPayment(paymentId, req?)	Refund a card payment
createEbarimt(req)	Create an electronic tax receipt
cancelEbarimt(paymentId)	Cancel an ebarimt by payment ID

QPayConfig

interface QPayConfig {
  baseUrl: string;      // QPay API base URL
  username: string;     // Merchant username
  password: string;     // Merchant password
  invoiceCode: string;  // Default invoice code
  callbackUrl: string;  // Payment callback URL
}

QPayError

class QPayError extends Error {
  statusCode: number;  // HTTP status code
  code: string;        // QPay error code
  rawBody: string;     // Raw response body
}

loadConfigFromEnv()

Loads a QPayConfig from environment variables. Throws an Error if any required variable is missing.

isQPayError(err)

Type guard that returns true if the given value is a QPayError instance.

License

MIT