Mempool

MCP (Model Context Protocol) server for the mempool.space Bitcoin API. No API key required.

Lets any MCP client (Claude Code, Claude Desktop, etc.) query live Bitcoin data: recommended fees, mempool state, blocks, transactions, addresses, price.

Tools

Tool	Arguments	Returns
get_recommended_fees	—	Fee estimates in sat/vB (fastest, 30 min, 1 h, economy, minimum)
get_mempool_stats	—	Unconfirmed tx count, total vsize, total pending fees
get_tip	—	Current block height and hash
get_recent_blocks	limit (1-10, default 5)	Recent blocks: height, time, tx count, median fee, mining pool
get_transaction	txid (64 hex chars)	Confirmation status, fee, fee rate, inputs/outputs
get_address	address	Confirmed balance, received total, tx counts, pending delta
get_price	—	BTC price in USD, EUR, GBP, CAD, CHF, AUD, JPY

Install and build

npm install
npm run build

Try it

examples/client.mjs spawns the server over stdio and calls each tool:

npm run example

Use with Claude Code

claude mcp add mempool -- node /path/to/mcp-mempool/dist/index.js

Then ask, for example: "quels frais je mets pour une transaction confirmée dans l'heure ?"

Use with Claude Desktop

Add to claude_desktop_config.json:

{
  "mcpServers": {
    "mempool": {
      "command": "node",
      "args": ["/path/to/mcp-mempool/dist/index.js"]
    }
  }
}

Other networks / self-hosted instance

Set MEMPOOL_API_BASE to point elsewhere (default: https://mempool.space/api):

{
  "mcpServers": {
    "mempool-testnet": {
      "command": "node",
      "args": ["/path/to/mcp-mempool/dist/index.js"],
      "env": { "MEMPOOL_API_BASE": "https://mempool.space/testnet4/api" }
    }
  }
}

Works with any mempool.space-compatible instance (e.g. a self-hosted one on your own node).

Notes

• Uses the public REST API; heavy usage should point MEMPOOL_API_BASE at a self-hosted instance (mempool.space rate-limits aggressively).
• API errors are returned as MCP tool errors (isError: true) with the upstream message, so the model can react to them.

License

MIT