x402 micropayment, live demo.

// stablekya.com/api/report — x402 gate
export default {
  async fetch(request: Request, env: Env) {
    const paymentSig = request.headers
      .get('PAYMENT-SIGNATURE');

    if (!paymentSig) {
      return new Response('Payment Required', {
        status: 402,
        headers: {
          'PAYMENT-REQUIRED': btoa(JSON.stringify({
            accepts: [{
              scheme: 'exact',
              network: 'base-sepolia',
              asset: 'USDC',
              amount: '1000',
              payTo: env.MERCHANT_ADDRESS,
              resource: 'kya-compliance-report-v1',
            }],
          })),
        },
      });
    }

    // Verify payment via facilitator...
    const report = await env.REPORTS
      .get('kya-report-v1.pdf');
    return new Response(report.body, {
      headers: {
        'Content-Type': 'application/pdf',
      },
    });
  },
};

// Stable402.com — x402 buyer flow
async function purchaseReport() {
  // 1. Hit the gate
  const res402 = await fetch(
    'https://stablekya.com/api/report'
  );
  const requirements = JSON.parse(atob(
    res402.headers.get('PAYMENT-REQUIRED')
  )).accepts[0];

  // 2. Sign EIP-3009 authorization
  const signature = await walletClient
    .signTypedData({
      domain: {
        name: 'USDC', version: '2',
        chainId: 84532,
        verifyingContract: USDC,
      },
      types: {
        TransferWithAuthorization: [
          /* from, to, value, ... */
        ],
      },
      message: {
        from: address,
        to: requirements.payTo,
        value: BigInt(requirements.amount),
      },
    });

  // 3. Retry with payment
  const res200 = await fetch(
    'https://stablekya.com/api/report',
    {
      headers: {
        'PAYMENT-SIGNATURE': btoa(
          JSON.stringify({
            x402Version: 2,
            accepted: requirements,
            payload: { signature },
          })
        ),
      },
    }
  );

  // 4. Deliver the PDF
  const pdf = await res200.blob();
  downloadPdf(pdf, 'kya-report.pdf');
}