STELLARPAY

The SDK — six packages

# one seller and one buyer, both real
npm install @stellarpay-sdk/express   # or /hono, /fastify
npm install @stellarpay-sdk/client

The whole integration

import { stellarpay } from "@stellarpay-sdk/core";
import { stellarpayExpress } from "@stellarpay-sdk/express";

const paywall = stellarpay({
  network: "stellar:testnet",
  payTo: "G…",
  routes: {
    "GET /weather": { price: "$0.001" },
  },
});

app.use(stellarpayExpress(paywall)); // before routes

import { createPayingFetch } from "@stellarpay-sdk/client";

const payFetch = createPayingFetch({
  secret: process.env.AGENT_SECRET,
  network: "stellar:testnet",
  limits: { maxPerCall: "$0.01", maxTotal: "$1.00" },
});

// 402 → pays → retries. Your code never sees it.
await payFetch("https://api.example/weather");

Change scheme on a route to settle over MPP instead of x402 — including server-sponsored gas, so the buyer pays no fees. Nothing else in your app changes.

Seven demos we built to prove it

All seven run live on Stellar testnet right now, selling real Horizon data for real money. Press the button on the dashboard and an autonomous agent goes shopping across them.

What actually happens on the wire

1. An agent requests a paid route. It gets a 402 with a machine-readable challenge — price, asset, recipient, network.
2. The client checks the price against its spend limits and refuses if it's over budget. This happens before anything is signed.
3. It signs and settles on Stellar — via the facilitator for x402, or directly for MPP, with gas optionally sponsored by the seller.
4. It retries automatically with proof of payment. Your calling code just sees a 200.
5. The seller's onPayment hook fires with a receipt carrying the real transaction hash — verifiable on any block explorer.