Attribute revenue with Paddle Checkout API

Before proceeding, confirm that you have linked your Paddle account.

The Paddle webhook routes events by reading custom_data.website_id.

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: {
      website_id: 'flid_******',
    },
  }),
});

Supported Paddle webhook events

• transaction.completed
• adjustment.created

Paddle's normalized webhook payload does not currently provide an email for matching, so do not rely on webhook-side visitor/session attribution from custom metadata alone.