Accept Agentic Payments with x402

npm install @coinbase/cdp-sdk @x402/fetch @x402/core @x402/evm @x402/svm @x402/extensions dotenv

import "dotenv/config";
import { CdpClient } from "@coinbase/cdp-sdk";

// Reads CDP_API_KEY_ID, CDP_API_KEY_SECRET, and CDP_WALLET_SECRET from env.
const cdp = new CdpClient();
const account = await cdp.evm.getOrCreateAccount({ name: "x402-checkouts-payer" });
console.log("Fund this EVM address with USDC:", account.address);

import "dotenv/config";
import { CdpClient } from "@coinbase/cdp-sdk";
import { applySpendControls, fromCdpEvmAccount } from "@coinbase/cdp-sdk/x402";
import { AuthCaptureEvmScheme } from "@x402/evm";
import { decodePaymentResponseHeader, wrapFetchWithPayment, x402Client } from "@x402/fetch";

const cdp = new CdpClient();
const account = await cdp.evm.getOrCreateAccount({ name: "x402-checkouts-payer" });
console.log("Paying from:", account.address);

// Register the auth-capture scheme for Base mainnet (checkouts are Base-only).
const signer = fromCdpEvmAccount(account);
const client = new x402Client().register(
  "eip155:8453",
  new AuthCaptureEvmScheme(signer),
);

// Refuse to sign anything larger than 5 USDC (6 decimals).
applySpendControls(client, { maxAmountPerPayment: { atomic: 5_000_000n } });

const fetchWithPayment = wrapFetchWithPayment(globalThis.fetch, client);

// Set X402_URL to the `x402_url` returned by Create Checkout (step 1).
const x402Url = process.env.X402_URL;
if (!x402Url) throw new Error("Set X402_URL to the x402_url returned by Create Checkout");

// The x402_url is a POST endpoint. Retry: a delayed signed POST can miss
// the challenge window and come back 402; a fresh attempt issues a new one.
let response;
for (let attempt = 0; attempt < 8; attempt++) {
  response = await fetchWithPayment(x402Url, { method: "POST" });
  if (response.ok) break;
}
const body = await response.text();
console.log(response.status, body);
if (!response.ok) {
  throw new Error(`Payment failed: ${response.status} ${body}`);
}

const settlement = response.headers.get("payment-response");
if (settlement) console.log(decodePaymentResponseHeader(settlement));