# Stripe Checkout Sessions This guide shows you how to integrate referral codes from Referral Rocket into your Stripe checkout sessions, allowing you to track referrals and attribute conversions properly. ### Step 1: Install Referral Rocket SDK First, install the Referral Rocket library by adding the script to the `` section of your website. Replace `YOUR-CAMPAIGN-ID` with your actual campaign ID. ```html ``` ### Step 2: Retrieve Referral Code Use the `getReferralCode()` function to retrieve the referral code stored in cookies. This function returns the referral code if available, or `null` if no referral code is found. ```javascript const referralCode = window.Rocket.getReferralCode(); console.log('Referral code:', referralCode); // Will log the code or null ``` ### Step 4: Create Stripe Checkout Session with Referral Code Stripe Checkout Sessions must be created **server-side** using your Stripe secret key. The referral code captured client-side needs to be sent to your server first, then included when creating the session. > **Important:** Never call `stripe.checkout.sessions.create` from the browser. It requires your Stripe secret key, which must never be exposed client-side. **Client-side** — send the referral code to your server when initiating checkout: ```javascript // On your checkout page (browser) const referralCode = window.Rocket.getReferralCode(); fetch('/create-checkout-session', { method: 'POST', headers: { 'Content-Type': 'application/json' }, body: JSON.stringify({ referralCode }) }); ``` **Server-side** — include the referral code as `client_reference_id` (Node.js example): ```javascript // On your server — never run this in the browser const session = await stripe.checkout.sessions.create({ success_url: "https://your-website.com/success", cancel_url: "https://your-website.com/cancel", client_reference_id: req.body.referralCode, // passed from client mode: "subscription", // or "payment" for one-time purchases line_items: [ { price: "price_1JZ2e2LzKb4YjC8Cw", // your Stripe price ID quantity: 1, } ] }); ```