Polygon Area

{
  "areaAcres": 121183721.9664,
  "areaHectares": 49041312.353,
  "areaKm2": 490413.12353,
  "areaM2": 490413123530.02,
  "asOf": "2026-10-11T08:41:07.797Z",
  "centroidLat": 37.57752478,
  "centroidLon": -95,
  "degraded": false,
  "disclaimer": "Screening signal computed from the named public source. Not financial, legal or investment advice; provided as is. Verify at the source before acting.",
  "method": "spherical excess, WGS84 authalic sphere (not ellipsoidal)",
  "notChecked": [
    "ellipsoidal geodesic area: this is a spherical (equal-area sphere, great-circle edges) area; against GeographicLib's ellipsoidal polygon area measured difference was 0.0009 percent for a 10 by 5 degre…",
    "the polygon's holes or multiple rings",
    "…2 more"
  ],
  "orientation": "COUNTERCLOCKWISE",
  "perimeterKm": 2875.86204,
  "perimeterM": 2875862.04,
  "reasons": [
    "Spherical area on the WGS84 authalic sphere; vertex order is counterclockwise."
  ],
  "selfIntersecting": false,
  "source": "Spherical excess on the WGS84 authalic sphere (R = 6371007.1809 m), computed locally",
  "summary": "4 vertices enclose 490413.1235 km2 (121183721.966 acres) with perimeter 2875.862 km.",
  "valid": true,
  "verdict": "COMPUTED",
  "vertices": 4
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i 'https://geo-calc.x402tookit.com/polygon-area?points=40%2C-100%3B40%2C-90%3B35%2C-90%3B35%2C-100'

# 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://geo-calc.x402tookit.com/polygon-area?points=40%2C-100%3B40%2C-90%3B35%2C-90%3B35%2C-100' \
  | 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 $0.02 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.02" });
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 $0.02 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Fgeo-calc.x402tookit.com%2Fpolygon-area
const res = await pay("https://geo-calc.x402tookit.com/polygon-area?points=40%2C-100%3B40%2C-90%3B35%2C-90%3B35%2C-100");
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 $0.02 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.02"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.get("https://geo-calc.x402tookit.com/polygon-area?points=40%2C-100%3B40%2C-90%3B35%2C-90%3B35%2C-100")
    print(res.status_code, res.text)