AI Integrations

CoinMarketCap x402

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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.

Pricing, features, and availability may change without prior notice. For production workloads, we recommend using the standard CoinMarketCap Pro API with an API key subscription.

What is x402?

x402 is an open payment protocol developed by Coinbase that enables instant, automatic stablecoin payments directly over HTTP. Instead of managing API keys and subscriptions, you pay per request using USDC on Base. Learn more at the x402 documentation.

How it works

Make a request to any x402-enabled endpoint. The server responds with HTTP 402 and a Payment-Required header containing the payment details (amount, network, asset, recipient).

Your wallet signs a USDC transferWithAuthorization (EIP-3009) message for the requested amount. This is an off-chain signature — no on-chain transaction occurs yet.

Resend the original request with the signed PAYMENT-SIGNATURE header attached. The facilitator verifies the signature, the server processes your request, and you receive the data. The on-chain USDC transfer is only executed upon successful data delivery.

MCP endpoint

The /x402/mcp endpoint exposes a Model Context Protocol server that supports x402 payments at the HTTP transport layer. This enables AI agents and LLM clients (e.g., Claude, Cursor) to discover and call CMC data tools with automatic per-request payment.

Connection URL:

Code
https://mcp.coinmarketcap.com/x402/mcp

Transport: Streamable HTTP (POST to /x402/mcp)

To connect, use any MCP-compatible client with an x402-aware HTTP transport that intercepts 402 responses, signs the payment, and retries. The MCP server exposes the same data tools as the REST endpoints below, and supports automatic tool discovery via the standard MCP tools/list method.

For standard MCP documentation, see CMC MCP.

Base URL

All x402 requests use the following base URL:

Code
https://pro-api.coinmarketcap.com

Supported REST endpoints

Endpoint	Method	Path	Description
DEX Search	GET	/x402/v1/dex/search	Search for DEX tokens by keyword (name, symbol, or contract address).
Cryptocurrency Quotes Latest	GET	/x402/v3/cryptocurrency/quotes/latest	Get the latest market quotes for one or more cryptocurrencies.
Cryptocurrency Listing Latest	GET	/x402/v3/cryptocurrency/listings/latest	Get a paginated list of all active cryptocurrencies with latest market data, ranked by market cap.
DEX Pairs Quotes Latest	GET	/x402/v4/dex/pairs/quotes/latest	Get the latest quotes and trading data for specific DEX trading pairs.

All parameters supported by the standard CoinMarketCap Pro API endpoints are also supported in their x402 counterparts. Refer to the linked documentation for full parameter details, limits, and response schemas. You can download the full list of IDs in a CSV file here.

Request examples

Example 1: Search DEX tokens by keyword:

Code
GET https://pro-api.coinmarketcap.com/x402/v1/dex/search?q=pepe

Example 2: Get latest quotes for Bitcoin and Ethereum by CoinMarketCap ID:

Code
GET https://pro-api.coinmarketcap.com/x402/v3/cryptocurrency/quotes/latest?id=1,1027

Example 3: Get the top 10 cryptocurrencies by market cap:

Code
GET https://pro-api.coinmarketcap.com/x402/v3/cryptocurrency/listings/latest?start=1&limit=10

Example 4: Get latest DEX pair quotes:

Code
GET https://pro-api.coinmarketcap.com/x402/v4/dex/pairs/quotes/latest?pair_address=0x...

Example 5: Using curl with a pre-signed payment header:

Code
curl --request GET \
  --url 'https://pro-api.coinmarketcap.com/x402/v1/dex/search?q=bnb' \
  -H 'PAYMENT-SIGNATURE: {{paymentSignature}}'

Pricing and payment

Current price: $0.01 USDC per API request across all supported endpoints.

Pricing is subject to change without prior notice. Always parse the Payment-Required response header for the current amount before signing.

Supported payment network:

• Base (Chain ID: 8453)

Payment asset:

• USDC on Base (0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913)

Payment method:

• EIP-3009 transferWithAuthorization — your wallet signs an off-chain authorization, and the facilitator executes the on-chain transfer only upon successful data delivery.

402 response format

When a request is made without a valid PAYMENT-SIGNATURE, the server returns HTTP 402 with a base64-encoded Payment-Required header:

Code
{
  "x402Version": 2,
  "error": "Payment required",
  "resource": {
    "url": "/x402/v1/dex/search",
    "description": "..."
  },
  "accepts": [
    {
      "scheme": "exact",
      "network": "eip155:8453",
      "asset": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
      "amount": "10000",
      "payTo": "0x271189c860DB25bC43173B0335784aD68a680908",
      "maxTimeoutSeconds": 30,
      "extra": {
        "name": "USD Coin",
        "version": "2"
      }
    }
  ]
}

Field	Description
scheme	Payment scheme, currently exact (EIP-3009 transferWithAuthorization)
network	Target chain in CAIP-2 format (eip155:8453 = Base Mainnet)
asset	USDC contract address on Base
amount	Payment amount in smallest unit (10000 = $0.01 USDC, 6 decimals)
payTo	Recipient address for the payment
maxTimeoutSeconds	Maximum validity window for the signed authorization
extra.name	EIP-712 domain name for the token (must be "USD Coin" for USDC on Base)
extra.version	EIP-712 domain version for the token

Quick start

Using the x402 TypeScript SDK

Install dependencies:

Code
npm install @x402/axios @x402/evm viem

Example — fetch DEX search results with automatic x402 payment:

Code
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";

const account = privateKeyToAccount("0xYOUR_PRIVATE_KEY");
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/v1/dex/search",
  { params: { q: "bnb" } },
);

console.log(response.data);

Using curl (manual flow)

Code
# Step 1: Get the 402 response with payment requirements
curl -s -D - 'https://pro-api.coinmarketcap.com/x402/v1/dex/search?q=bnb'

# Step 2: Sign the payment using your x402 client (SDK or custom implementation)

# Step 3: Retry with the payment signature
curl --request GET \
  --url 'https://pro-api.coinmarketcap.com/x402/v1/dex/search?q=bnb' \
  -H 'PAYMENT-SIGNATURE: <your-signed-payment>'

Important notes

• No API key required — x402 payment replaces traditional API key authentication.
• Pay only on success — the on-chain USDC transfer is executed only when the server successfully returns data. If the server encounters an error, no payment is deducted.
• Authorization expiry — signed authorizations expire after maxTimeoutSeconds (typically 30s). Unused authorizations are never submitted on-chain.
• EIP-712 domain — when constructing the transferWithAuthorization signature, use name: "USD Coin" and version: "2" for the USDC token domain on Base.
• Rate limits — x402 endpoints may have separate rate limits from the standard Pro API. Refer to the Payment-Required response for the latest terms.