Food Barcode

{
  "allergens": [
    "milk",
    "nuts",
    "soybeans"
  ],
  "brands": "Nutella, Ferrero",
  "categories": [
    "Spreads",
    "Sweet spreads",
    "Hazelnut spreads"
  ],
  "found": true,
  "name": "Nutella",
  "nova_group": 4,
  "nutriscore_grade": "e",
  "nutrition_per_100g": {
    "energy_kcal": 539,
    "fat_g": 30.9,
    "proteins_g": 6.3,
    "sugars_g": 56.3
  },
  "quantity": "400 g",
  "source": "Open Food Facts (ODbL/CC-BY-SA)",
  "upc": "3017620422003"
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i 'https://saylorinnovations.com/api/food/barcode/:upc'

# 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://saylorinnovations.com/api/food/barcode/:upc' \
  | 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 $0.01 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.01" });
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 $0.01 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Fsaylorinnovations.com%2Fapi%2Ffood%2Fbarcode%2F%3Aupc
const res = await pay("https://saylorinnovations.com/api/food/barcode/:upc");
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 $0.01 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.01"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.get("https://saylorinnovations.com/api/food/barcode/:upc")
    print(res.status_code, res.text)