For AI agents: llms.txt is a short guide that sends you to the rules your problem needs, and rules.json holds every rule of this playbook as JSON.

Applies when

The project it takes payments.

Cost

Paid. Stripe charges a fee per transaction. No open source service can move card payments, because that needs a licensed payment provider.

How to do it

Stripe's npm package dates from 2011 and its 1.0.0 shipped in December 2011. Version 23.0.0 shipped on 1 October 2026. The npm package had about 14.5 million weekly downloads in October 2026, and the Python package about 10.7 million. Both are MIT-licensed. Since September 2024, Stripe ships a backwards-compatible API version every month and a breaking release twice a year. Each SDK release pins the API version it was built for, so upgrade as Pin the provider's API version says. To leave, ask Stripe to send saved cards to another PCI DSS Level 1 processor as an encrypted JSON file. Copy orders, invoices and subscriptions out through the API, because the card export leaves them out. Build the checkout as Choose a checkout that keeps you on SAQ A says. Choose something else when you want a merchant of record to collect and pay sales tax and VAT for you. Paddle does that, but its current SDKs reached 1.0 in 2024, so record the exception. Adyen suits large card volumes, and Mollie suits local European payment methods.

Examples

Using these examples: they show one way to follow this rule. Keep the behaviour and the check, not the syntax. Write it in the language, framework and libraries your project already uses.

JavaScript example

import Stripe from 'stripe';

const stripe = new Stripe(process.env.STRIPE_SECRET_KEY);

export const startCheckout = (order) => stripe.checkout.sessions.create({
  mode: 'payment',
  line_items: [{ price: order.priceId, quantity: 1 }],
  success_url: 'https://example.com/orders/done',
}, { idempotencyKey: `checkout-${order.id}` });

Python example

import os
import stripe

stripe.api_key = os.environ["STRIPE_SECRET_KEY"]

def start_checkout(order):
    return stripe.checkout.Session.create(
        mode="payment",
        line_items=[{"price": order.price_id, "quantity": 1}],
        success_url="https://example.com/orders/done",
        idempotency_key=f"checkout-{order.id}",
    )

How to check

The lock file pins one Stripe SDK major version, and the webhook endpoint uses the API version that SDK pins. Every payment form runs on a Stripe-hosted page or embedded field.

Sources

• Stripe API versioning
• Request a payment data export

Related rules

• Pin the provider's API version in Payments
• Choose a checkout that keeps you on SAQ A in Payments