NutriRef — pay-per-call USDA nutrition for AI agents

Structured FoodData Central data behind x402 micropayments. No signup, no API keys, no auth flows — agents pay $0.001 – $0.005 per request in USDC on Base.

Endpoints

Method	Path	Price	Returns
GET	/v1/nutrition/search?q=&limit=	$0.001	Ranked food matches (fdc_id + macros)
GET	/v1/nutrition/detail/{fdc_id}	$0.002	Full normalized nutrition (13 nutrients)
POST	/v1/nutrition/compare	$0.003	2–5 foods side by side + per-nutrient winners
POST	/v1/nutrition/recipe	$0.005	Scaled + summed nutrition for a recipe

How payment works

An x402-aware HTTP client handles it automatically. Unpaid requests return 402 Payment Required with payment instructions; the client signs a gasless USDC authorization (EIP-3009) and retries. The facilitator settles on-chain.

Call it from Python

from x402.client import x402Client
from x402.http.clients.httpx import wrapHttpxWithPayment
from x402.mechanisms.evm.exact import register_exact_evm_client
from eth_account import Account
import asyncio

account = Account.from_key("0x...your-funded-wallet-key...")  # needs USDC on Base
client = x402Client(); register_exact_evm_client(client, account)

async def main():
    async with wrapHttpxWithPayment(client, base_url="https://nutriref.xyz") as http:
        r = await http.get("/v1/nutrition/detail/2012128")
        print(r.json())

asyncio.run(main())

Network

Chain Base mainnet (chain id 8453)
Asset USDC — 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913
Receiver 0x3f0a7f839619D578b8EEeD741C26F418b8E98e97

Use it from Claude / MCP agents

NutriRef ships an MCP server wrapper. Any agent that speaks MCP (Claude Desktop, Claude Code, etc.) plugs it in with one config block:

{
  "mcpServers": {
    "nutriref": {
      "command": "python",
      "args": ["-m", "mcp_server"],
      "env": {
        "PAYER_PRIVATE_KEY": "0x...your-funded-wallet-key...",
        "NUTRIREF_BASE_URL": "https://nutriref.xyz"
      }
    }
  }
}

Source & install: github.com/Younghef/nutriref-api (pip install ".[mcp]").

Machine-readable

/openapi.json — full OpenAPI spec · /docs — Swagger UI · /.well-known/x402 — x402 Bazaar discovery · /llms.txt — LLM-readable summary · /.well-known/ai-plugin.json — AI plugin manifest