Source: https://datafa.st/docs/paddle-checkout-api
Markdown source: https://datafa.st/docs/paddle-checkout-api.md
Description: Set up revenue attribution with Paddle Checkout API. Pass DataFast cookies as custom data for accurate marketing channel attribution.

# Attribute revenue with Paddle Checkout API

← [Revenue attribution guide](/docs/revenue-attribution-guide)

# Attribute revenue with Paddle Checkout API

> Make sure you've [connected your Paddle account](/docs/connect-payment-provider) first.

Pass `custom_data` with `datafast_visitor_id` and `datafast_session_id` (cookies from DataFast) when creating a checkout transaction:

```javascript
// app/api/create-checkout/route.js
import { cookies } from 'next/headers';

export async function POST() {
  const cookieStore = cookies();
  // If you're using Next.js 15+, use this instead:
  // const cookieStore = await cookies();

  const response = await fetch('https://api.paddle.com/transactions', {
    method: 'POST',
    headers: {
      'Authorization': `Bearer ${PADDLE_API_KEY}`,
      'Content-Type': 'application/json',
    },
    body: JSON.stringify({
      items: [...],
      custom_data: {
        datafast_visitor_id: cookieStore.get('datafast_visitor_id')?.value,
        datafast_session_id: cookieStore.get('datafast_session_id')?.value
      }
    })
  });

  const data = await response.json();
  return Response.json(data);
}
```

Once connected and custom data is properly passed, DataFast will automatically attribute revenue to the correct marketing channels. **No webhook setup is required**.

> After receiving a successful payment, you should see revenue data in your dashboard (referrer, country, browser, etc.).