Subnet Vlsm

{
  "addressesPerSubnet": null,
  "allocations": [
    {
      "broadcast": "192.168.1.127",
      "cidr": "192.168.1.0/25",
      "firstUsable": "192.168.1.1",
      "fitsInParent": true,
      "lastUsable": "192.168.1.126",
      "name": "Sales",
      "netmask": "255.255.255.128",
      "network": "192.168.1.0",
      "prefix": 25,
      "requestedHosts": 100,
      "totalAddresses": 128,
      "usableHosts": 126,
      "wastedAddresses": 26
    },
    {
      "broadcast": "192.168.1.191",
      "cidr": "192.168.1.128/26",
      "firstUsable": "192.168.1.129",
      "fitsInParent": true,
      "lastUsable": "192.168.1.190",
      "name": "Eng",
      "netmask": "255.255.255.192",
      "network": "192.168.1.128",
      "prefix": 26,
      "requestedHosts": 50,
      "totalAddresses": 64,
      "usableHosts": 62,
      "wastedAddresses": 12
    }
  ],
  "asOf": "2026-10-11T14:45:32.356Z",
  "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.",
  "fits": true,
  "freeBlocks": [
    {
      "addresses": 4,
      "cidr": "192.168.1.244/30"
    },
    {
      "addresses": 8,
      "cidr": "192.168.1.248/29"
    }
  ],
  "mode": "vlsm",
  "network": "192.168.1.0/24",
  "notChecked": [
    "whether the space is allocated to you or overlaps existing routes",
    "growth: each subnet is sized for exactly the hosts asked for, with no spare room",
    "…2 more"
  ],
  "reasons": [
    "Subnets are placed largest first, each aligned on its own boundary, so no space is lost to misalignment.",
    "Each subnet is the smallest power of two holding the hosts plus network and broadcast addresses (a /31 point-to-point link has no broadcast, RFC 3021)."
  ],
  "source": "RFC 4632 CIDR and RFC 3021 /31 arithmetic, computed locally",
  "subnetCount": 5,
  "subnetPrefix": null,
  "subnets": [],
  "summary": "5 subnets allocated from 192.168.1.0/24, using 244 of 256 addresses (95.31%).",
  "totalAddresses": 256,
  "usableHostsPerSubnet": null,
  "usedAddresses": 244,
  "utilizationPercent": 95.3125,
  "verdict": "ALLOCATED"
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i 'https://network-calc.x402tookit.com/subnet-vlsm?hosts=Sales%3A100%2CEng%3A50%2CLab%3A25%2CMgmt%3A10%2CWAN%3A2&network=192.168.1.0%2F24'

# 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://network-calc.x402tookit.com/subnet-vlsm?hosts=Sales%3A100%2CEng%3A50%2CLab%3A25%2CMgmt%3A10%2CWAN%3A2&network=192.168.1.0%2F24' \
  | 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%2Fnetwork-calc.x402tookit.com%2Fsubnet-vlsm
const res = await pay("https://network-calc.x402tookit.com/subnet-vlsm?hosts=Sales%3A100%2CEng%3A50%2CLab%3A25%2CMgmt%3A10%2CWAN%3A2&network=192.168.1.0%2F24");
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://network-calc.x402tookit.com/subnet-vlsm?hosts=Sales%3A100%2CEng%3A50%2CLab%3A25%2CMgmt%3A10%2CWAN%3A2&network=192.168.1.0%2F24")
    print(res.status_code, res.text)