# CMC x402

GitHub repo: [coinmarketcap-official/skills-for-ai-agents-by-CoinMarketCap](https://github.com/coinmarketcap-official/skills-for-ai-agents-by-CoinMarketCap)

Pay-per-request crypto market data powered by the x402 protocol. Access CoinMarketCap endpoints instantly with on-chain USDC payment. No API key or subscription required.

## What is x402?

x402 is an open payment protocol developed by Coinbase that enables automatic stablecoin payments over HTTP. Instead of managing API keys, you pay **$0.01 USDC** per request on Base. The x402 client library handles payment signing automatically.

Learn more: [https://docs.x402.org](https://docs.x402.org)

## Prerequisites

- **Node.js 18+** and npm installed
- **Base network wallet** with a private key you control
- **USDC on Base** to pay for requests ($0.01 per request)
- **Small amount of ETH on Base** for gas fees

## Quick Start

Install the x402 TypeScript SDK:

```bash
npm install @x402/axios @x402/evm viem
```

Fetch data with automatic payment:

```typescript
import { createX402AxiosClient } from "@x402/axios";
import { ExactEvmScheme, toClientEvmSigner } from "@x402/evm";
import { privateKeyToAccount } from "viem/accounts";
import { createPublicClient, http } from "viem";
import { base } from "viem/chains";

// SECURITY: Never hardcode private keys in source code.
// Use environment variables: process.env.PRIVATE_KEY
const account = privateKeyToAccount(process.env.PRIVATE_KEY as `0x${string}`);
const publicClient = createPublicClient({ chain: base, transport: http() });
const signer = toClientEvmSigner(account, publicClient);

const client = createX402AxiosClient({
  schemes: [new ExactEvmScheme(signer)],
});

const response = await client.get(
  "https://pro-api.coinmarketcap.com/x402/v3/cryptocurrency/quotes/latest",
  { params: { symbol: "BTC,ETH" } }
);

console.log(response.data);
```

## Endpoints

Base URL: `https://pro-api.coinmarketcap.com`

| Endpoint | Path | Use For |
|----------|------|---------|
| Quotes | `/x402/v3/cryptocurrency/quotes/latest` | Current prices for specific coins |
| Listings | `/x402/v3/cryptocurrency/listings/latest` | Top coins by market cap |
| DEX Search | `/x402/v1/dex/search` | Find DEX tokens by keyword |
| DEX Pairs | `/x402/v4/dex/pairs/quotes/latest` | DEX pair trading data |

All parameters from the standard CMC Pro API work with x402 endpoints.

## Use Cases

- **Get current prices for specific coins:** Use `/x402/v3/cryptocurrency/quotes/latest` with symbol or id parameter
- **List top cryptocurrencies:** Use `/x402/v3/cryptocurrency/listings/latest` with limit parameter
- **Search for DEX tokens:** Use `/x402/v1/dex/search` with keyword parameter
- **Get DEX pair trading data:** Use `/x402/v4/dex/pairs/quotes/latest` with pair address
- **AI agent data access:** Use the MCP endpoint at `https://mcp.coinmarketcap.com/x402/mcp`

## MCP for AI Agents

The x402 MCP endpoint lets AI agents access CMC data with automatic payment.

**Connection URL:**
```
https://mcp.coinmarketcap.com/x402/mcp
```

**Transport:** Streamable HTTP (POST)

Connect using any MCP client with an x402-aware HTTP transport. The server exposes the same tools as the REST endpoints and supports automatic tool discovery.

## Pricing

**$0.01 USDC** per request on Base (Chain ID: 8453).

Payment only occurs on successful data delivery. If the request fails, no payment is deducted.

## Resources

- [x402 Protocol](https://x402.org)
- [x402 Documentation](https://docs.x402.org)
- [x402 GitHub](https://github.com/coinbase/x402)
- [CMC API Documentation](https://coinmarketcap.com/api/documentation)