Express

better-payment/express turns the payment handler into Express middleware. It has no dependencies and works with Express 4 and 5.

1. Create the payment instanceCopy Anchor Link

// payment.ts
import { betterPayment, iyzico } from 'better-payment';

export const payment = betterPayment({
  mode: process.env.NODE_ENV === 'production' ? 'production' : 'sandbox',
  providers: {
    iyzico: iyzico({
      apiKey: process.env.IYZICO_API_KEY!,
      secretKey: process.env.IYZICO_SECRET_KEY!,
    }),
  },
  handler: {
    onCallback: async (result) => markOrder(result.paymentId, result.status),
    callbackRedirect: (result) => `/orders/${result.paymentId}?payment=${result.status}`,
  },
});

See configuration for every option and handler for allowedActions, transformRequest and the other handler hooks.

2. Mount the handlerCopy Anchor Link

// server.ts
import express from 'express';
import { toExpressHandler } from 'better-payment/express';
import { payment } from './payment';

const app = express();
app.all('/api/pay/*path', toExpressHandler(payment)); // Express 4: '/api/pay/*'

app.listen(3000);

You don't need express.json() or express.urlencoded() for the payment routes, because the adapter reads the raw body. If a body parser runs first, its result is used. Unexpected errors are passed to next(error).

3. Start a paymentCopy Anchor Link

The routes are served under /api/pay, so the frontend calls them directly:

const res = await fetch('/api/pay/iyzico/payment/init-3ds', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify(paymentRequest),
});

The typed client (better-payment/client) wraps the same routes.

4. Callback URLsCopy Anchor Link

Set callbackUrl to https://yoursite.com/api/pay/<provider>/payment/complete-3ds. The handler verifies the callback, calls onCallback and redirects the customer with callbackRedirect.

For PayTR, set the notification URL in the PayTR panel to https://yoursite.com/api/pay/paytr/callback.

Request body sizeCopy Anchor Link

The adapter reads at most 1 MiB of a request body and answers 413 for larger ones. Bank callbacks are a few kB. Change the limit with maxBodySize (in bytes):

app.all('/api/pay/*path', toExpressHandler(payment, { maxBodySize: 64 * 1024 }));