Book Signatures

{
  "alternatives": [
    {
      "blankPages": 0,
      "pagesPerSignature": 4,
      "signatures": 25
    },
    {
      "blankPages": 4,
      "pagesPerSignature": 8,
      "signatures": 13
    }
  ],
  "asOf": "2026-10-12T01:48:13.893Z",
  "blankPages": 12,
  "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.",
  "leaves": 56,
  "notChecked": [
    "mixed signature sizes (many books finish with a smaller signature, such as an 8 or 4, instead of blanks)",
    "paper grain direction and the imposition scheme of your press",
    "…1 more"
  ],
  "pages": 100,
  "pagesPerSignature": 16,
  "reasons": [
    "A folded sheet gives a signature of 16 pages; the last signature is padded with blanks (or replaced by a smaller one)."
  ],
  "sheetsAllCopies": 28,
  "sheetsNoteBothSides": "A sheet printed on both sides makes 4 pages.",
  "sheetsPerCopy": 28,
  "signatures": 7,
  "source": "computed locally (folding arithmetic)",
  "spineThicknessNote": "Count sheets x paper caliper for spine width.",
  "summary": "100 pages in 7 signature(s) of 16 = 112 pages, 12 blank page(s).",
  "totalPages": 112,
  "verdict": "BLANKS_NEEDED"
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i 'https://paper-print-calc.x402tookit.com/book-signatures?pages=100&pagesPerSignature=16'

# 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://paper-print-calc.x402tookit.com/book-signatures?pages=100&pagesPerSignature=16' \
  | 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%2Fpaper-print-calc.x402tookit.com%2Fbook-signatures
const res = await pay("https://paper-print-calc.x402tookit.com/book-signatures?pages=100&pagesPerSignature=16");
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://paper-print-calc.x402tookit.com/book-signatures?pages=100&pagesPerSignature=16")
    print(res.status_code, res.text)