Unit Price

{
  "asOf": "2026-10-11T23:32:57.211Z",
  "bestName": "Large",
  "bestPricePerStandardUnit": 0.8378,
  "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.",
  "notChecked": [
    "coupons, loyalty prices, tax and deposits",
    "quality, brand, shelf life or waste",
    "…1 more"
  ],
  "ranked": [
    {
      "amount": 1,
      "name": "Large",
      "price": 3.8,
      "pricePerStandardUnit": 0.8378,
      "unit": "lb"
    },
    {
      "amount": 16,
      "name": "Small",
      "price": 4,
      "pricePerStandardUnit": 0.8818,
      "unit": "oz"
    }
  ],
  "reasons": [
    "All prices converted to a standard unit: per 100 g."
  ],
  "savingsBestVsWorstPercent": 40.2,
  "source": "computed locally (exact unit definitions)",
  "standardUnit": "100 g",
  "summary": "Best value is Large at 0.8378 per 100 g, 40.2% cheaper than Bulk.",
  "verdict": "BEST_FOUND",
  "worstName": "Bulk"
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i 'https://shipping-calc.x402tookit.com/unit-price?items=%5B%7B%22name%22%3A%22Small%22%2C%22price%22%3A4%2C%22amount%22%3A16%2C%22unit%22%3A%22oz%22%7D%2C%7B%22name%22%3A%22Large%22%2C%22price%22%3A3.8%2C%22amount%22%3A1%2C%22unit%22%3A%22lb%22%7D%2C%7B%22name%22%3A%22Bulk%22%2C%22price%22%3A7%2C%22amount%22%3A500%2C%22unit%22%3A%22g%22%7D%5D'

# 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://shipping-calc.x402tookit.com/unit-price?items=%5B%7B%22name%22%3A%22Small%22%2C%22price%22%3A4%2C%22amount%22%3A16%2C%22unit%22%3A%22oz%22%7D%2C%7B%22name%22%3A%22Large%22%2C%22price%22%3A3.8%2C%22amount%22%3A1%2C%22unit%22%3A%22lb%22%7D%2C%7B%22name%22%3A%22Bulk%22%2C%22price%22%3A7%2C%22amount%22%3A500%2C%22unit%22%3A%22g%22%7D%5D' \
  | 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%2Fshipping-calc.x402tookit.com%2Funit-price
const res = await pay("https://shipping-calc.x402tookit.com/unit-price?items=%5B%7B%22name%22%3A%22Small%22%2C%22price%22%3A4%2C%22amount%22%3A16%2C%22unit%22%3A%22oz%22%7D%2C%7B%22name%22%3A%22Large%22%2C%22price%22%3A3.8%2C%22amount%22%3A1%2C%22unit%22%3A%22lb%22%7D%2C%7B%22name%22%3A%22Bulk%22%2C%22price%22%3A7%2C%22amount%22%3A500%2C%22unit%22%3A%22g%22%7D%5D");
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://shipping-calc.x402tookit.com/unit-price?items=%5B%7B%22name%22%3A%22Small%22%2C%22price%22%3A4%2C%22amount%22%3A16%2C%22unit%22%3A%22oz%22%7D%2C%7B%22name%22%3A%22Large%22%2C%22price%22%3A3.8%2C%22amount%22%3A1%2C%22unit%22%3A%22lb%22%7D%2C%7B%22name%22%3A%22Bulk%22%2C%22price%22%3A7%2C%22amount%22%3A500%2C%22unit%22%3A%22g%22%7D%5D")
    print(res.status_code, res.text)