Stripe API Integration

For custom checkout flows, you can pass the referral ID directly through the Stripe API.

Implementation Steps

1. Add the PromoteKit Script

Add the PromoteKit script to your website. It should be on both your landing page (where referrals arrive) and your checkout page.

The script works across subdomains, so you can use it on both yoursite.com and app.yoursite.com.

2. Retrieve the Referral ID

After the script loads, you can access the referral ID:

JavaScript/TypeScript: Use window.promotekit_referral

PHP: Use $_COOKIE['promotekit_referral']

3. Pass to Stripe

Include the referral ID in the metadata when creating a checkout session or subscription:

const session = await stripe.checkout.sessions.create({
  success_url: 'https://example.com/success',
  cancel_url: 'https://example.com/cancel',
  metadata: {
    promotekit_referral: req.body.referral,
  },
  line_items: [
    { price: 'price_1OBQlV2eZvKYlo2CDL02DbMx', quantity: 1 },
  ],
  mode: 'subscription',
});

Manual Signup Tracking

For tracking users who sign up before they pay, use the refer function:

window.promotekit.refer(email, stripe_customer_id)

This allows you to attribute the referral even before payment occurs.