X402 Monetize

npx awal@2.12.1 address

mkdir x402-server && cd x402-server
npm init -y
npm install express @x402/express @x402/core @x402/evm @x402/extensions

const express = require("express");
const { paymentMiddleware } = require("@x402/express");
const { x402ResourceServer, HTTPFacilitatorClient } = require("@x402/core/server");
const { ExactEvmScheme } = require("@x402/evm/exact/server");

const app = express();
app.use(express.json());

const PAY_TO = "<address from step 1>";

// Create facilitator client and x402 resource server
const facilitator = new HTTPFacilitatorClient({ url: "https://x402.org/facilitator" });
const server = new x402ResourceServer(facilitator);
server.register("eip155:8453", new ExactEvmScheme());

// x402 payment middleware — protects routes below
app.use(
  paymentMiddleware(
    {
      "GET /api/example": {
        accepts: {
          scheme: "exact",
          price: "$0.01",
          network: "eip155:8453",
          payTo: PAY_TO,
        },
        description: "Description of what this endpoint returns",
        mimeType: "application/json",
      },
    },
    server,
  ),
);

// Protected endpoint
app.get("/api/example", (req, res) => {
  res.json({ data: "This costs $0.01 per request" });
});

app.listen(3000, () => console.log("Server running on port 3000"));

node index.js

curl -i http://localhost:3000/api/example

const { x402ResourceServer, HTTPFacilitatorClient } = require("@x402/core/server");
const { ExactEvmScheme } = require("@x402/evm/exact/server");

const facilitator = new HTTPFacilitatorClient({ url: "https://x402.org" });
const server = new x402ResourceServer(facilitator);
server.register("eip155:8453", new ExactEvmScheme());

{
  "GET /api/data": {
    accepts: {
      scheme: "exact",
      price: "$0.05",
      network: "eip155:8453",
      payTo: "0x...",
    },
    description: "Human-readable description of the endpoint",
    mimeType: "application/json",
    extensions: {
      ...declareDiscoveryExtension({
        output: {
          example: { result: "example response" },
          schema: {
            properties: {
              result: { type: "string" },
            },
          },
        },
      }),
    },
  },
}

const { declareDiscoveryExtension } = require("@x402/extensions/bazaar");

extensions: {
  ...declareDiscoveryExtension({
    output: {
      example: { /* example response body */ },
      schema: {
        properties: {
          /* JSON schema of the response */
        },
      },
    },
  }),
}

app.use(
  paymentMiddleware(
    {
      "GET /api/cheap": {
        accepts: {
          scheme: "exact",
          price: "$0.001",
          network: "eip155:8453",
          payTo: PAY_TO,
        },
        description: "Inexpensive data lookup",
      },
      "GET /api/expensive": {
        accepts: {
          scheme: "exact",
          price: "$1.00",
          network: "eip155:8453",
          payTo: PAY_TO,
        },
        description: "Premium data access",
      },
      "POST /api/query": {
        accepts: {
          scheme: "exact",
          price: "$0.25",
          network: "eip155:8453",
          payTo: PAY_TO,
        },
        description: "Run a custom query",
      },
    },
    server,
  ),
);

app.get("/api/cheap", (req, res) => { /* ... */ });
app.get("/api/expensive", (req, res) => { /* ... */ });
app.post("/api/query", (req, res) => { /* ... */ });

app.use(
  paymentMiddleware(
    {
      "GET /api/*": {
        accepts: {
          scheme: "exact",
          price: "$0.05",
          network: "eip155:8453",
          payTo: PAY_TO,
        },
        description: "API access",
      },
    },
    server,
  ),
);

app.get("/api/users", (req, res) => { /* ... */ });
app.get("/api/posts", (req, res) => { /* ... */ });

app.get("/health", (req, res) => res.json({ status: "ok" }));

// Payment middleware only applies to routes registered after it
app.use(paymentMiddleware({ /* ... */ }, server));
app.get("/api/data", (req, res) => { /* ... */ });

app.use(
  paymentMiddleware(
    {
      "POST /api/analyze": {
        accepts: {
          scheme: "exact",
          price: "$0.10",
          network: "eip155:8453",
          payTo: PAY_TO,
        },
        description: "Analyze text sentiment",
        mimeType: "application/json",
        extensions: {
          ...declareDiscoveryExtension({
            output: {
              example: { sentiment: "positive", score: 0.95 },
              schema: {
                properties: {
                  sentiment: { type: "string" },
                  score: { type: "number" },
                },
              },
            },
          }),
        },
      },
    },
    server,
  ),
);

app.post("/api/analyze", (req, res) => {
  const { text } = req.body;
  // ... your logic
  res.json({ sentiment: "positive", score: 0.95 });
});

"GET /api/data": {
  accepts: [
    {
      scheme: "exact",
      price: "$0.01",
      network: "eip155:8453",
      payTo: EVM_ADDRESS,
    },
    {
      scheme: "exact",
      price: "$0.01",
      network: "eip155:84532",
      payTo: EVM_ADDRESS,
    },
  ],
  description: "Data endpoint accepting Base mainnet or testnet",
}

npm install @coinbase/x402

const { facilitator } = require("@coinbase/x402");
const { HTTPFacilitatorClient } = require("@x402/core/server");

const facilitatorClient = new HTTPFacilitatorClient(facilitator);
const server = new x402ResourceServer(facilitatorClient);
server.register("eip155:8453", new ExactEvmScheme());

# Check the endpoint's payment requirements
npx awal@2.12.1 x402 details http://localhost:3000/api/example

# Make a paid request
npx awal@2.12.1 x402 pay http://localhost:3000/api/example