Ref Airport

{
  "data": {
    "airport": {
      "country": "NL",
      "elevation_ft": -11,
      "iata": "AMS",
      "icao": "EHAM",
      "lat": 52.3086,
      "lon": 4.76389,
      "municipality": "Amsterdam",
      "name": "Amsterdam Airport Schiphol",
      "region": "NL-NH",
      "timezone": "Europe/Amsterdam",
      "type": "large_airport"
    },
    "found": true,
    "matched_on": "iata"
  },
  "meta": {
    "computed_at": "2026-09-28T12:00:00.000Z",
    "deterministic": true,
    "disclaimer": "Factual output of a deterministic computation over public data. Provided as is, with no warranty of accuracy, completeness or availability. Not investment, financial, legal, tax, medical or any other professional advice, and not a recommendation. Verify before relying on it. Terms: https://api.duoleads.com/terms",
    "price_usd": "0.05",
    "request_id": "01K6B7Q4ZC8H3F2M9WXR5TYN0D",
    "sources": [
      {
        "attribution": "OurAirports (public domain)",
        "id": "ourairports",
        "licence": "Public Domain",
        "published": "2026-09-28",
        "version": "2026-09-28 extract"
      },
      {
        "attribution": "Time zones derived from timezone-boundary-builder data (https://github.com/evansiroky/timezone-boundary-builder), (c) contributors, ODbL 1.0, via timezonefinder 9.0.0",
        "id": "timezone-boundary-builder",
        "licence": "ODbL-1.0",
        "published": "2026-09-29",
        "version": "2026d"
      }
    ]
  },
  "ok": true,
  "route": "/v1/ref/airport",
  "version": "1.0.0"
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i 'https://api.duoleads.com/v1/ref/airport?code=AMS'

# x402 v2 sends the challenge base64-encoded in the PAYMENT-REQUIRED header (v1 sends it in the body).
# To read the header:
curl -sS -g -o /dev/null -D - 'https://api.duoleads.com/v1/ref/airport?code=AMS' \
  | grep -i '^payment-required:' | cut -d' ' -f2 | tr -d '\r' | base64 --decode

// npm i @x402/fetch @x402/evm viem
import { wrapFetchWithPayment, x402Client } from "@x402/fetch";
import { registerExactEvmScheme } from "@x402/evm/exact/client";
import { privateKeyToAccount } from "viem/accounts";

// Pays at most $0.05 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.05" });
registerExactEvmScheme(client, { signer: privateKeyToAccount(process.env.EVM_PRIVATE_KEY) });
const pay = wrapFetchWithPayment(fetch, client);

// Not sure it's safe to pay? ToolVet checks it first for $0.005. Pay for that from a separate
// client: this one is capped at $0.05 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Fapi.duoleads.com%2Fv1%2Fref%2Fairport
const res = await pay("https://api.duoleads.com/v1/ref/airport?code=AMS");
console.log(res.status, await res.text());

# pip install "x402[requests,evm]"
import os
from eth_account import Account
from x402 import x402ClientSync
from x402.http.clients import x402_requests
from x402.mechanisms.evm import EthAccountSigner
from x402.mechanisms.evm.exact.register import register_exact_evm_client

# Pays at most $0.05 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.05"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.get("https://api.duoleads.com/v1/ref/airport?code=AMS")
    print(res.status_code, res.text)