Monetize Service

Overview

Build and deploy a paid API that other agents can use via x402. Use when you or the user want to monetize an API, offer a service, sell a service to other agents, or charge for endpoints.

How it works

x402 is an HTTP-native payment protocol. When a client hits a protected endpoint without paying, the server returns HTTP 402 with payment requirements. The client signs a USDC payment and retries with a payment header. The facilitator verifies and settles the payment, and the server returns the response.

Prerequisites

Must be authenticated (npx awal@latest status to check)

1. Get the payment address

Get the wallet address that will receive payments:

npx awal@latest address

Use this address as the payTo value in your server configuration.

2. Set up the project

mkdir x402-server && cd x402-server
npm init -y
npm install express x402-express

Create index.js:

const express = require("express");
const { paymentMiddleware } = require("x402-express");

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

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

// x402 payment middleware
const payment = paymentMiddleware(PAY_TO, {
  "GET /api/example": {
    price: "$0.01",
    network: "base",
    config: {
      description: "Description of what this endpoint returns",
    },
  },
});

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

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

3. Run and test

node index.js

Test with curl (should get a 402 response with payment requirements):

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

Test with a paid request:

npx awal@latest x402 pay http://localhost:3000/api/example

API reference

paymentMiddleware(payTo, routes, facilitator?)

Parameter	Type	Description
`payTo`	string	Ethereum address (0x…) to receive USDC payments
`routes`	object	Route config mapping route patterns to payment config
`facilitator`	object?	Optional custom facilitator (defaults to x402.org)

Route config

Each key is "METHOD /path". The value is either a price string or a config object:

// Simple — just a price
{ "GET /api/data": "$0.05" }

// Full config
{
  "POST /api/query": {
    price: "$0.25",
    network: "base",
    config: {
      description: "Human-readable description",
      inputSchema: {
        bodyType: "json",
        bodyFields: {
          query: { type: "string", description: "The query to run" },
        },
      },
      outputSchema: {
        type: "object",
        properties: {
          result: { type: "string" },
        },
      },
    },
  },
}

Route config fields

Field	Type	Description
`price`	string	USDC price (e.g. “ $0.01", "$ 1.00”)
`network`	string	Blockchain network: “base” or “base-sepolia”
`config.description`	string?	What this endpoint does (shown to clients)
`config.inputSchema`	object?	Expected request body/query schema
`config.outputSchema`	object?	Response body schema
`config.maxTimeoutSeconds`	number?	Max time for payment settlement

Patterns

Multiple endpoints with different prices

const payment = paymentMiddleware(PAY_TO, {
  "GET /api/cheap": { price: "$0.001", network: "base" },
  "GET /api/expensive": { price: "$1.00", network: "base" },
  "POST /api/query": { price: "$0.25", network: "base" },
});

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

Health check (no payment)

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

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

POST with body schema

const payment = paymentMiddleware(PAY_TO, {
  "POST /api/analyze": {
    price: "$0.10",
    network: "base",
    config: {
      description: "Analyze text sentiment",
      inputSchema: {
        bodyType: "json",
        bodyFields: {
          text: { type: "string", description: "Text to analyze" },
        },
      },
      outputSchema: {
        type: "object",
        properties: {
          sentiment: { type: "string" },
          score: { type: "number" },
        },
      },
    },
  },
});

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

Using the CDP facilitator

For production use with the Coinbase facilitator:

npm install @coinbase/x402

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

const payment = paymentMiddleware(PAY_TO, routes, facilitator);

This requires CDP_API_KEY_ID and CDP_API_KEY_SECRET environment variables from the CDP Portal.

Pricing guidelines

Use Case	Suggested Price
Simple data lookup	$0.001 -$ 0.01
API proxy / enrichment	$0.01 -$ 0.10
Compute-heavy query	$0.10 -$ 0.50
AI inference	$0.05 -$ 1.00

Checklist

Get wallet address with npx awal@latest address
Install express and x402-express
Define routes with prices and descriptions
Register payment middleware before protected routes
Keep health/status endpoints before payment middleware
Test with curl (should get 402) and npx awal@latest x402 pay (should get 200)
Announce your service so other agents can find and use it

GET STARTED

WALLETS

PAYMENTS

STABLECOINS

TRADING

ONCHAIN TOOLS

CUSTOMERS

WEBHOOKS

CONSUMER APIS

BUSINESS APIS

INSTITUTIONAL APIS

Overview

How it works

Prerequisites

1. Get the payment address

2. Set up the project

3. Run and test

API reference

paymentMiddleware(payTo, routes, facilitator?)

Route config

Route config fields

Patterns

Multiple endpoints with different prices

Health check (no payment)

POST with body schema

Using the CDP facilitator

Pricing guidelines

Checklist

​Overview

​How it works

​Prerequisites

​1. Get the payment address

​2. Set up the project

​3. Run and test

​API reference

​paymentMiddleware(payTo, routes, facilitator?)

​Route config

​Route config fields

​Patterns

​Multiple endpoints with different prices

​Health check (no payment)

​POST with body schema

​Using the CDP facilitator

​Pricing guidelines

​Checklist

Overview

How it works

Prerequisites

1. Get the payment address

2. Set up the project

3. Run and test

API reference

paymentMiddleware(payTo, routes, facilitator?)

Route config

Route config fields

Patterns

Multiple endpoints with different prices

Health check (no payment)

POST with body schema

Using the CDP facilitator

Pricing guidelines

Checklist