Resource Server Guide

import type { PaymentRequirement } from "@xentfi/x402-facilitator";

const requirement: PaymentRequirement = {
  scheme: "eip3009",
  network: "base-mainnet",
  blockchainId: "2fad7eb1-4405-4400-af4f-2b37401a6bd6",
  assetId: "b3d641bb-f28f-4d1f-b89c-a504ad51f453",
  maxAmountRequired: "1.00",
  payTo: "0xYourWalletAddress",
  resource: "GET /premium-report",
  maxTimeoutSeconds: 3600,
};

import Fastify from "fastify";
import { X402FacilitatorClient } from "@xentfi/x402-facilitator";
import type { PaymentPayload, PaymentRequirement } from "@xentfi/x402-facilitator";

const facilitator = new X402FacilitatorClient({
  apiKey: process.env.WAAS_API_KEY!,
  orgId: process.env.WAAS_ORG_ID!,
});

const app = Fastify();

app.get("/premium-report", async (req, reply) => {
  const proofHeader = req.headers["x-payment"];

  if (!proofHeader) {
    // No payment attached yet — issue the 402 challenge.
    return reply.status(402).send({
      x402Version: 1,
      accepts: [requirement],
    });
  }

  const paymentPayload: PaymentPayload = JSON.parse(
    Buffer.from(proofHeader as string, "base64").toString("utf8"),
  );

  try {
    // Throws on invalid signature, expired authorization, wrong amount, etc.
    await facilitator.verify(paymentPayload, requirement);

    // Submits the TransferWithAuthorization on-chain via your WAAS relayer wallet.
    const settlement = await facilitator.settle(paymentPayload, requirement);

    return {
      report: "... the actual paid content ...",
      txHash: settlement.txHash,
    };
  } catch (error) {
    return reply.status(402).send({
      x402Version: 1,
      accepts: [requirement],
      error: (error as Error).message,
    });
  }
});

app.listen({ port: 3000 });