Monetize Your MCP Server with x402 in 5 Minutes

What You'll Build

You have an MCP server (or any API endpoint). You want to charge agents per call — fractions of a cent, settled instantly in USDC on Base. No signups, no API key management, no monthly billing. Just: agent calls → agent pays → you get USDC.

The flow:

1. Agent hits your endpoint
2. You return 402 Payment Required with price + payment address
3. Agent signs the payment and retries
4. You verify the payment and serve the response
5. USDC lands in your wallet, settled on Base (~$0.001 gas)

Step 1: Add x402 Middleware (3 minutes)

If you're running an Express/Node server:

// x402 middleware — add to your Express app
const X402_PRICE_USDC = 0.01; // 1 cent per call
const X402_RECEIVER = '0xYOUR_WALLET'; // your Base wallet

app.use((req, res, next) => {
  // Check for x402 payment header
  const payment = req.headers['x-402-payment'];

  if (!payment || !verifyPayment(payment, X402_PRICE_USDC, X402_RECEIVER)) {
    res.status(402).set({
      'X-402-Protocol': '1.0',
      'X-402-Price': X402_PRICE_USDC.toString(),
      'X-402-Asset': 'USDC',
      'X-402-Chain': 'base',
      'X-402-Receiver': X402_RECEIVER,
      'Content-Type': 'application/json'
    }).json({
      error: 'Payment Required',
      price: X402_PRICE_USDC,
      asset: 'USDC',
      chain: 'base',
      receiver: X402_RECEIVER,
      message: `Pay ${X402_PRICE_USDC} USDC to use this endpoint`
    });
    return;
  }
  next();
});

For Python/FastAPI:

# x402 middleware for FastAPI
from fastapi import Request, HTTPException
from fastapi.responses import JSONResponse

X402_PRICE = 0.01
X402_RECEIVER = "0xYOUR_WALLET"

@app.middleware("http")
async def x402_middleware(request: Request, call_next):
    payment = request.headers.get("x-402-payment")
    if not payment or not verify_payment(payment, X402_PRICE, X402_RECEIVER):
        return JSONResponse(
            status_code=402,
            content={"error": "Payment Required", "price": X402_PRICE, "asset": "USDC", "chain": "base", "receiver": X402_RECEIVER},
            headers={"X-402-Protocol": "1.0", "X-402-Price": str(X402_PRICE), "X-402-Chain": "base", "X-402-Receiver": X402_RECEIVER}
        )
    return await call_next(request)

Step 2: Add Discovery Endpoint (1 minute)

Create a /.well-known/x402 endpoint so crawlers and agent directories can discover your paid service:

// Add to your server
app.get('/.well-known/x402', (req, res) => {
  res.json({
    protocol: 'x402',
    version: 2,
    name: 'Your MCP Server Name',
    description: 'What your service does',
    payment: {
      network: 'eip155:8453',    // Base
      asset: '0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913', // USDC on Base
      receiver: '0xYOUR_WALLET',
      price: 0.01
    },
    endpoints: {
      catalog: '/tools',
      docs: '/docs'
    }
  });
});

Step 3: List on minia2a.uk for Agent Discovery (1 minute)

Once your x402 endpoint is live, register it on minia2a.uk — the marketplace where AI agents discover paid services:

curl -X POST https://minia2a.uk/api/v1/register-simple \
  -H "Content-Type: application/json" \
  -d '{
    "name": "my-mcp-server",
    "endpoint": "https://my-server.com/tools",
    "description": "What my MCP server does",
    "priceCents": 1
  }'

Your service immediately appears in the agent-queryable catalog at /x402/preview. Agents can discover it, test it with free credits, and start paying per call.

Why This Works

The x402 Foundation Backs This

On July 14, 2026, the x402 Foundation launched under the Linux Foundation with 40 members including Visa, Mastercard, Stripe, Google, AWS, Shopify, Coinbase, and Circle. The protocol has processed 109+ million transactions. It's the emerging standard for machine-to-machine payments.

With the Foundation providing neutral governance, x402 is no longer "Coinbase's experiment" — it's the industry-wide standard for agentic commerce. If you build an x402-compatible service today, you're building on infrastructure that the entire payments industry is converging on.

Real Services, Real Usage

The most popular paid services on minia2a.uk right now (by trial usage):

Tags: x402, MCP, monetization, micropayments, USDC, Base, agent economy
Published: August 1, 2026 · minia2a.uk/blog/monetize-mcp-x402