Stripe

This guide is the canonical reference for the Stripe sale path. Other framework guides (Next.js, Express, etc.) link here for Step 3. If you need click capture or signup tracking first, start with the Next.js guide or the framework guide for your stack.

PrerequisitesCopy Anchor Link

• Your program ID (program menu → Program settings → Business)
• A program API key (program menu → Program settings, then Developers → API keys)
• Stripe Checkout or Stripe Billing already working in your app
• Your Stripe account connected to the program (program menu → Program settings → Payments, Connect Stripe). Affitor then receives the account's events through Stripe Connect; you do not add a webhook

1. Capture clicks and track signupsCopy Anchor Link

These two steps are identical to the framework integration. Follow Step 1 and Step 2 in the Next.js guide, or your framework's equivalent.

The key thing to take away: when you call signup(userId) or trackLead({ customerExternalId: userId }), keep that userId — you will attach it to every Checkout Session as affitor_customer_key.

2. Attach Affitor metadata to the Checkout SessionCopy Anchor Link

When you create a Stripe Checkout Session on your server, attach three metadata fields: affitor_click_id, affitor_customer_key, and program_id.

How to read affitor_click_id server-side: the browser SDK stores the click id in a first-party cookie called affitor_click_id. Read it from the incoming HTTP request and forward it to your server. For example, in a Next.js Route Handler you can read cookies().get('affitor_click_id')?.value. In a plain Express handler you can read req.cookies.affitor_click_id.

One-time payment (mode: 'payment')Copy Anchor Link

const session = await stripe.checkout.sessions.create({
  mode: 'payment',
  line_items: [{ price: 'price_xxx', quantity: 1 }],
  success_url: 'https://yoursite.com/success',
  cancel_url:  'https://yoursite.com/cancel',
  metadata: {
    affitor_click_id:      clickId,          // from the affitor_click_id cookie
    affitor_customer_key:  user.id,          // SAME id you used at signup
    program_id:            'YOUR_PROGRAM_ID',
  },
});

Affitor listens to the checkout.session.completed webhook event and attributes the payment automatically. No extra call needed.

Subscription (mode: 'subscription')Copy Anchor Link

For subscriptions, put the same fields in subscription_data.metadata. Affitor records a subscription's first payment and each renewal from the invoice events (invoice.payment_succeeded, invoice.paid), and an invoice carries the subscription's metadata, not the Checkout Session's. Renewals do not depend on it: once the first payment is attributed, Affitor saves the buyer's Stripe customer ID and matches each renewal by the buyer's email or that Stripe customer ID.

const session = await stripe.checkout.sessions.create({
  mode: 'subscription',
  line_items: [{ price: 'price_xxx', quantity: 1 }],
  success_url: 'https://yoursite.com/success',
  cancel_url:  'https://yoursite.com/cancel',
  metadata: {
    affitor_click_id:      clickId,
    affitor_customer_key:  user.id,
    program_id:            'YOUR_PROGRAM_ID',
  },
  // The subscription's invoices (first payment and renewals) read the click from here
  subscription_data: {
    metadata: {
      affitor_click_id:      clickId,
      affitor_customer_key:  user.id,
      program_id:            'YOUR_PROGRAM_ID',
    },
  },
});

3. How Affitor attributes paymentsCopy Anchor Link

Affitor processes these Stripe webhook events for sales:

Attribution fallback chain. Affitor resolves the partner in this order:

1. affitor_click_id: direct click attribution (most reliable)
2. Email: matched against the lead record if affitor_click_id is missing
3. Stripe customer ID: matched if the same customer appeared in a previous attributed session
4. client_reference_id: used only when the metadata has no click. The Affitor tracker writes the click there on Payment Links, the Buy Button and the Pricing Table, which cannot carry metadata
5. affitor_customer_key alone: matched against the lead record as a last resort

Supplying all three fields (affitor_click_id, affitor_customer_key, program_id) on every checkout is the recommended default — it ensures Affitor can attribute the sale even if the click cookie expired or was blocked.

Subscription RenewalsCopy Anchor Link

If you self-host the Stripe webhook and call trackSale yourself (rather than relying on Affitor's Connect webhook), renewals need their own handler. The first payment fires as checkout.session.completed — every subsequent renewal arrives as a separate invoice.paid event with billing_reason: 'subscription_cycle'. Without a dedicated case, every renewal commission is silently missed.

Attribution rides on the affitor_customer_key you planted in subscription_data.metadata at checkout creation — Stripe copies that onto the Subscription, and Stripe stamps it onto every renewal invoice.

Two nuances matter:

• Skip $0 renewals. 100%-off coupons and fully credit-covered cycles produce invoice.paid events with amount_paid of 0. The SDK rejects a non-positive amount, so guard against it.
• Stripe Basil metadata path. Stripe API version Basil (2025-03-31+) moved subscription_details under invoice.parent. Pre-Basil accounts still expose it at the legacy top level (invoice.subscription_details). Read the Basil path first and fall back to the legacy one so the handler works on both.

Add this as a separate case in the same Stripe webhook handler that processes checkout.session.completed:

case 'invoice.paid': {
  const invoice = event.data.object;
  // Only renewals — the first invoice is already counted at checkout.session.completed.
  if (invoice.billing_reason !== 'subscription_cycle') break;
  // Skip $0 renewals (100%-off coupons, fully credit-covered) — the SDK rejects a non-positive amount.
  if (!invoice.amount_paid || invoice.amount_paid <= 0) break;
  await affitor.trackSale({
    // Stripe Basil (2025-03-31+) moved subscription_details under invoice.parent;
    // read the Basil path first, fall back to the legacy top-level for pre-Basil accounts.
    customerExternalId: invoice.parent?.subscription_details?.metadata?.affitor_customer_key
      ?? invoice.subscription_details?.metadata?.affitor_customer_key,
    amount: invoice.amount_paid,            // integer cents
    invoiceId: invoice.id,                  // idempotency key — 409 = already recorded
    isRecurring: true,
    saleType: 'subscription',
    // Basil relocated the subscription id under invoice.parent.subscription_details;
    // fall back to the legacy top-level invoice.subscription for pre-Basil accounts.
    subscriptionId: invoice.parent?.subscription_details?.subscription
      ?? (typeof invoice.subscription === 'string' ? invoice.subscription : invoice.subscription?.id),
  });
  break;
}

4. Alternative: server-side tracking (non-Stripe)Copy Anchor Link

If you are not using Stripe Checkout, or you need to report a sale from a different payment provider, call the server SDK directly after the payment is confirmed:

import Affitor from '@affitor/sdk/server';
const affitor = new Affitor({ apiKey: process.env.AFFITOR_API_KEY! });

await affitor.trackSale({
  customerExternalId: user.id,   // SAME id as signup
  amount:             4999,      // integer cents
  invoiceId:          invoice.id, // idempotency key — duplicate returns 409
  currency:           'usd',     // optional, defaults to usd
  isRecurring:        false,     // true for renewals
});

This path requires a Bearer API key and is called from your server only — never from the browser.

VerifyCopy Anchor Link

Common mistakesCopy Anchor Link