Blackbody

{
  "areaM2": 6082104400000000000,
  "asOf": "2026-10-11T08:56:11.700Z",
  "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.",
  "emissivity": 1,
  "notChecked": [
    "the real emissivity, which varies with wavelength and surface (stars and planets are not perfect blackbodies)",
    "absorbed or reflected incoming radiation: this is emission only, not a net heat balance",
    "…1 more"
  ],
  "peakBand": "green",
  "radiantExitanceWM2": 62938592.5,
  "reasons": [
    "Wien: lambda_max = 2.897771955e-3 m K / T. Stefan-Boltzmann: M = emissivity x sigma x T^4, sigma = 5.670374419e-8 W/m2/K4 (CODATA 2018).",
    "The wavelength peak and the frequency peak are different points of the same curve."
  ],
  "sigma": 5.670374419e-8,
  "source": "computed locally",
  "summary": "At 5772 K the emission peaks at 502.04 nm (green) and radiates 62938600 W per square metre. Over 6082100000000000000 m2 that is 3.82799e+26 W.",
  "temperatureK": 5772,
  "totalPowerW": 3.8279909e+26,
  "verdict": "COMPUTED",
  "wienB": 0.002897771955,
  "wienPeakFrequencyHz": 339331595000000,
  "wienPeakWavelengthM": 5.02039493e-7,
  "wienPeakWavelengthNm": 502.03949
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i 'https://physics-calc.x402tookit.com/blackbody?radiusM=695700000&temperatureK=5772'

# 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://physics-calc.x402tookit.com/blackbody?radiusM=695700000&temperatureK=5772' \
  | 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%2Fphysics-calc.x402tookit.com%2Fblackbody
const res = await pay("https://physics-calc.x402tookit.com/blackbody?radiusM=695700000&temperatureK=5772");
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://physics-calc.x402tookit.com/blackbody?radiusM=695700000&temperatureK=5772")
    print(res.status_code, res.text)