payments

SKILL.md

Stripe Payments Integration

You are an expert in Stripe payments for Vercel-deployed applications — covering the native Vercel Marketplace integration, Checkout Sessions, webhook handling, subscription billing, and the Stripe Node.js SDK.

Vercel Marketplace Setup (Recommended)

Stripe is a native Vercel Marketplace integration with sandbox provisioning and unified billing.

Install via Marketplace

# Install Stripe from Vercel Marketplace (auto-provisions sandbox + env vars)
vercel integration add stripe

Auto-provisioned environment variables:

  • STRIPE_SECRET_KEY — server-side API key
  • STRIPE_PUBLISHABLE_KEY — client-side publishable key
  • STRIPE_WEBHOOK_SECRET — webhook endpoint signing secret

SDK Setup

# Server-side SDK
npm install stripe

# Client-side SDK (for Stripe Elements / Checkout)
npm install @stripe/stripe-js @stripe/react-stripe-js

Initialize the Stripe Client

// lib/stripe.ts
import Stripe from "stripe";

export const stripe = new Stripe(process.env.STRIPE_SECRET_KEY!, {
  apiVersion: "2026-02-25.clover",
  typescript: true,
});

Checkout Sessions

Server Action (Recommended for 2026)

Server Actions are the preferred pattern for creating Checkout Sessions in Next.js 15+, eliminating the need for API routes:

// app/actions/checkout.ts
"use server";
import { redirect } from "next/navigation";
import { stripe } from "@/lib/stripe";

export async function createCheckoutSession(priceId: string) {
  const session = await stripe.checkout.sessions.create({
    mode: "payment",
    line_items: [{ price: priceId, quantity: 1 }],
    success_url: `${process.env.NEXT_PUBLIC_APP_URL}/success?session_id={CHECKOUT_SESSION_ID}`,
    cancel_url: `${process.env.NEXT_PUBLIC_APP_URL}/cancel`,
  });

  redirect(session.url!);
}
// app/pricing/page.tsx
import { createCheckoutSession } from "@/app/actions/checkout";

export default function PricingPage() {
  return (
    <form action={createCheckoutSession.bind(null, "price_xxx")}>
      <button type="submit">Buy Now</button>
    </form>
  );
}

Create a Checkout Session (API Route)

// app/api/checkout/route.ts
import { NextResponse } from "next/server";
import { stripe } from "@/lib/stripe";

export async function POST(req: Request) {
  const { priceId } = await req.json();

  const session = await stripe.checkout.sessions.create({
    mode: "payment", // or "subscription" for recurring
    payment_method_types: ["card"],
    line_items: [{ price: priceId, quantity: 1 }],
    success_url: `${process.env.NEXT_PUBLIC_APP_URL}/success?session_id={CHECKOUT_SESSION_ID}`,
    cancel_url: `${process.env.NEXT_PUBLIC_APP_URL}/cancel`,
  });

  return NextResponse.json({ url: session.url });
}

Redirect to Checkout (Client)

"use client";
import { loadStripe } from "@stripe/stripe-js";

const stripePromise = loadStripe(process.env.NEXT_PUBLIC_STRIPE_PUBLISHABLE_KEY!);

export function CheckoutButton({ priceId }: { priceId: string }) {
  const handleCheckout = async () => {
    const res = await fetch("/api/checkout", {
      method: "POST",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify({ priceId }),
    });
    const { url } = await res.json();
    window.location.href = url;
  };

  return <button onClick={handleCheckout}>Subscribe</button>;
}

Webhook Handling

Stripe sends events to your webhook endpoint for asynchronous payment processing. Always verify the signature.

// app/api/webhook/stripe/route.ts
import { NextResponse } from "next/server";
import { stripe } from "@/lib/stripe";
import Stripe from "stripe";

export async function POST(req: Request) {
  const body = await req.text();
  const signature = req.headers.get("stripe-signature")!;

  let event: Stripe.Event;
  try {
    event = stripe.webhooks.constructEvent(
      body,
      signature,
      process.env.STRIPE_WEBHOOK_SECRET!
    );
  } catch (err) {
    return NextResponse.json({ error: "Invalid signature" }, { status: 400 });
  }

  switch (event.type) {
    case "checkout.session.completed": {
      const session = event.data.object as Stripe.Checkout.Session;
      // Fulfill the order — update database, send confirmation, etc.
      break;
    }
    case "invoice.payment_succeeded": {
      const invoice = event.data.object as Stripe.Invoice;
      // Handle successful subscription renewal
      break;
    }
    case "customer.subscription.deleted": {
      const subscription = event.data.object as Stripe.Subscription;
      // Handle cancellation — revoke access
      break;
    }
  }

  return NextResponse.json({ received: true });
}

Important: Webhook routes must read the raw body as text (not JSON) for signature verification. Do not add bodyParser or JSON middleware to webhook routes.

Subscription Billing

Create a Subscription Checkout

const session = await stripe.checkout.sessions.create({
  mode: "subscription",
  line_items: [{ price: priceId, quantity: 1 }],
  success_url: `${process.env.NEXT_PUBLIC_APP_URL}/dashboard`,
  cancel_url: `${process.env.NEXT_PUBLIC_APP_URL}/pricing`,
});

Customer Portal

Allow customers to manage their subscriptions:

// app/api/portal/route.ts
import { stripe } from "@/lib/stripe";

export async function POST(req: Request) {
  const { customerId } = await req.json();

  const session = await stripe.billingPortal.sessions.create({
    customer: customerId,
    return_url: `${process.env.NEXT_PUBLIC_APP_URL}/dashboard`,
  });

  return Response.json({ url: session.url });
}

Embedded Checkout (Recommended)

Stripe's Embedded Checkout renders inside your page via an iframe, keeping users on your domain while offloading PCI compliance to Stripe:

// app/actions/embedded-checkout.ts
"use server";
import { stripe } from "@/lib/stripe";

export async function createEmbeddedCheckout(priceId: string) {
  const session = await stripe.checkout.sessions.create({
    mode: "payment",
    line_items: [{ price: priceId, quantity: 1 }],
    ui_mode: "embedded",
    return_url: `${process.env.NEXT_PUBLIC_APP_URL}/success?session_id={CHECKOUT_SESSION_ID}`,
  });

  return { clientSecret: session.client_secret! };
}
"use client";
import { loadStripe } from "@stripe/stripe-js";
import { EmbeddedCheckoutProvider, EmbeddedCheckout } from "@stripe/react-stripe-js";
import { createEmbeddedCheckout } from "@/app/actions/embedded-checkout";

const stripePromise = loadStripe(process.env.NEXT_PUBLIC_STRIPE_PUBLISHABLE_KEY!);

export function CheckoutEmbed({ priceId }: { priceId: string }) {
  return (
    <EmbeddedCheckoutProvider
      stripe={stripePromise}
      options={{ fetchClientSecret: () => createEmbeddedCheckout(priceId).then(r => r.clientSecret) }}
    >
      <EmbeddedCheckout />
    </EmbeddedCheckoutProvider>
  );
}

Stripe Elements (Custom Forms)

"use client";
import { Elements, PaymentElement, useStripe, useElements } from "@stripe/react-stripe-js";
import { loadStripe } from "@stripe/stripe-js";

const stripePromise = loadStripe(process.env.NEXT_PUBLIC_STRIPE_PUBLISHABLE_KEY!);

function CheckoutForm() {
  const stripe = useStripe();
  const elements = useElements();

  const handleSubmit = async (e: React.FormEvent) => {
    e.preventDefault();
    if (!stripe || !elements) return;

    const { error } = await stripe.confirmPayment({
      elements,
      confirmParams: { return_url: `${window.location.origin}/success` },
    });

    if (error) console.error(error.message);
  };

  return (
    <form onSubmit={handleSubmit}>
      <PaymentElement />
      <button type="submit" disabled={!stripe}>Pay</button>
    </form>
  );
}

export function PaymentForm({ clientSecret }: { clientSecret: string }) {
  return (
    <Elements stripe={stripePromise} options={{ clientSecret }}>
      <CheckoutForm />
    </Elements>
  );
}

Environment Variables

Variable Scope Description
STRIPE_SECRET_KEY Server API secret key (starts with sk_)
STRIPE_PUBLISHABLE_KEY Client Publishable key (starts with pk_)
NEXT_PUBLIC_STRIPE_PUBLISHABLE_KEY Client Alias exposed to browser via Next.js
STRIPE_WEBHOOK_SECRET Server Webhook signing secret (starts with whsec_)

Cross-References

  • Marketplace install and env var provisioning⤳ skill: marketplace
  • Webhook route patterns⤳ skill: routing-middleware
  • Environment variable management⤳ skill: env-vars
  • Serverless function config⤳ skill: vercel-functions

Official Documentation

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