io.github.CryptoAPIs-io/mcp-broadcast

@cryptoapis-io/mcp-broadcast

MCP server for Crypto APIs Broadcast product. Submit locally signed transactions to the blockchain.

API Version: Compatible with Crypto APIs version 2024-12-12

Features

• Broadcast signed transaction hex to any supported blockchain
• Supports EVM (Ethereum, Ethereum Classic, BSC, Polygon, Avalanche (C-Chain), Arbitrum, Base, Optimism, Tron)
• Supports UTXO (Bitcoin, Bitcoin Cash, Litecoin, Dogecoin, Dash, Zcash)
• Works with transactions signed by @cryptoapis-io/mcp-signer or any external signer

Prerequisites

• Node.js 18+
• Crypto APIs account and API key (sign up | get API key)

Installation

npm install @cryptoapis-io/mcp-broadcast

Or install all Crypto APIs MCP servers: npm install @cryptoapis-io/mcp

Usage

# Run with API key
npx @cryptoapis-io/mcp-broadcast --api-key YOUR_API_KEY

# Or use environment variable
export CRYPTOAPIS_API_KEY=YOUR_API_KEY
npx @cryptoapis-io/mcp-broadcast

# HTTP transport
npx @cryptoapis-io/mcp-broadcast --transport http --port 3000 --api-key YOUR_API_KEY

Claude Desktop

Add to your Claude Desktop config (~/Library/Application Support/Claude/claude_desktop_config.json on macOS, %APPDATA%\Claude\claude_desktop_config.json on Windows):

{
  "mcpServers": {
    "cryptoapis-broadcast": {
      "command": "npx",
      "args": ["-y", "@cryptoapis-io/mcp-broadcast"],
      "env": {
        "CRYPTOAPIS_API_KEY": "your_api_key_here"
      }
    }
  }
}

Cursor

Add to .cursor/mcp.json (project) or ~/.cursor/mcp.json (global):

{
  "mcpServers": {
    "cryptoapis-broadcast": {
      "command": "npx",
      "args": ["-y", "@cryptoapis-io/mcp-broadcast"],
      "env": {
        "CRYPTOAPIS_API_KEY": "your_api_key_here"
      }
    }
  }
}

MCP Inspector

npx @modelcontextprotocol/inspector npx @cryptoapis-io/mcp-broadcast --api-key YOUR_API_KEY

n8n

1. Start the server in HTTP mode:

   npx @cryptoapis-io/mcp-broadcast --transport http --port 3000 --api-key YOUR_API_KEY
   

2. In your n8n workflow, add an AI Agent node
3. Under Tools, add an MCP Client Tool and set the URL to http://localhost:3000/mcp

All servers default to port 3000. Use --port to assign different ports when running multiple servers.

Available Tools

broadcast_signed_transaction

Submit a signed transaction to the blockchain.

Parameter	Description
blockchain	Target blockchain (ethereum, bitcoin, binance-smart-chain, tron, polygon, etc.)
network	Network (mainnet, testnet, sepolia, mordor, nile, amoy, fuji, etc.)
signedTransactionHex	The signed transaction hex string to broadcast

CLI Arguments

Argument	Description	Default
--api-key	Crypto APIs API key	CRYPTOAPIS_API_KEY env var
--transport	Transport type: stdio or http	stdio
--host	HTTP host	0.0.0.0
--port	HTTP port	3000
--path	HTTP path	/mcp
--stateless	Enable stateless HTTP mode	false

HTTP API Key Modes

When using HTTP transport, the server supports two API key modes:

• With --api-key: The key is used for all requests. x-api-key request headers are ignored.
• Without --api-key: Each request must include an x-api-key header with a valid Crypto APIs key. This enables hosting a public server where each user provides their own key.

# Per-request key mode (multi-tenant)
npx @cryptoapis-io/mcp-broadcast --transport http --port 3000
# Clients send x-api-key header with each request

Stdio transport always requires an API key at startup.

Important: API Key Required

Warning: Making requests without a valid API key — or with an incorrect one — may result in your IP being banned from the Crypto APIs ecosystem. Always ensure a valid API key is configured before starting any server.

Remote MCP Server

Crypto APIs provides an official remote MCP server with all tools available via HTTP Streamable transport at https://ai.cryptoapis.io/mcp. Pass your API key via the x-api-key header — no installation required.

License

MIT