Dev Number Base Converter

{
  "result": {
    "answer": "255",
    "answerLabel": "Base 16 ff in base 10",
    "details": [
      {
        "label": "Binary",
        "value": "11111111"
      },
      {
        "label": "Octal",
        "value": "377"
      },
      {
        "label": "Decimal",
        "value": "255"
      },
      {
        "label": "Hexadecimal",
        "value": "FF"
      }
    ],
    "steps": [
      "Parse \"ff\" in base 16 → decimal 255",
      "Render decimal 255 in base 10 → \"255\""
    ],
    "value": null
  },
  "tool": "number-base-converter"
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i 'https://agentstoolshub.com/api/v1/dev/number-base-converter?from=16&to=10&value=ff'

# 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://agentstoolshub.com/api/v1/dev/number-base-converter?from=16&to=10&value=ff' \
  | 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 $0.002 per call.
const client = new x402Client().setSpendControls({ maxAmountPerPayment: "$0.002" });
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 $0.002 per payment. GET https://toolvet.app/api/v1/check?url=https%3A%2F%2Fagentstoolshub.com%2Fapi%2Fv1%2Fdev%2Fnumber-base-converter
const res = await pay("https://agentstoolshub.com/api/v1/dev/number-base-converter?from=16&to=10&value=ff");
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 $0.002 per call.
client = x402ClientSync().set_spend_controls({"max_amount_per_payment": "$0.002"})
register_exact_evm_client(client, EthAccountSigner(Account.from_key(os.environ["EVM_PRIVATE_KEY"])))

with x402_requests(client) as session:
    res = session.get("https://agentstoolshub.com/api/v1/dev/number-base-converter?from=16&to=10&value=ff")
    print(res.status_code, res.text)