nullbuilds/x402-mcp

x402-mcp

MCP server for the x402 payment protocol. Browse 13,000+ live paid APIs via the Bazaar catalog, inspect payment requirements, and check wallet balances — without touching a private key.

npmgithubv0.1.2live

Install

Add to your Claude Desktop config:

{
  "mcpServers": {
    "x402": {
      "command": "npx",
      "args": ["@nullbuilds/x402-mcp"]
    }
  }
}

No API keys. No wallet setup. Works immediately.

What it does

x402 is Coinbase's HTTP payment protocol — services return 402 Payment Requiredand agents pay in USDC to access them. Coinbase's Bazaar catalog lists every registered service. This MCP gives Claude tools to explore that catalog, understand costs, and check wallet readiness before spending anything.

Tools

discover_paid_servicesread-only

Browse the Bazaar catalog of x402-enabled APIs. Returns services with cost, network, and endpoint URL.

querystringSearch by name or description(optional)
networkstringFilter by network: base, solana, ethereum(optional)
limitnumberResults to return (max 100, default 20)(optional)
offsetnumberPagination offset(optional)
get_service_detailsread-only

Get full payment requirements for a specific resource URL — all options, networks, and pricing.

resource_urlstringExact URL of the x402 resource
estimate_paymentread-only

Probe a URL live and return its x402 payment requirements. No payment is made.

resource_urlstringURL to probe
methodGET|POSTHTTP method (default GET)(optional)
check_wallet_balanceread-only

Check the USDC balance of any wallet address on Base. Read-only — no private key required.

wallet_addressstring0x address or ENS name

Example

Find Twitter intelligence services:

discover_paid_services({ query: "twitter", network: "base" })
Found 3 service(s):

- mesh.heurist.xyz (Base, 0.01 USDC)
  URL: https://mesh.heurist.xyz/x402/agents/ElfaTwitterIntelligenceAgent/search_mentions
  Search for mentions of specific tokens or topics on Twitter.

- mesh.heurist.xyz (Base, 0.05 USDC)
  URL: https://mesh.heurist.xyz/x402/agents/ElfaTwitterIntelligenceAgent/get_smart_mentions
  Get smart mentions with engagement metrics and sentiment analysis.

Check what it costs before paying:

estimate_payment({ resource_url: "https://mesh.heurist.xyz/x402/agents/ElfaTwitterIntelligenceAgent/search_mentions" })
Payment estimate for: https://mesh.heurist.xyz/...
Payment options (1):

### Option 1
- Cost: 0.01 USDC on Base
- Recipient: 0x3b5...
- Timeout: 30s

No payment was made. This is an estimate only.

Roadmap

v0.1 ✓Discovery, estimation, balance check
v0.2make_x402_request — pay and call via CDP Server Wallets
v0.3Payment history, spending limits, multi-chain