Due Date

{
  "asOf": "2026-10-11T08:36:50.084Z",
  "computedForDate": "2026-03-12",
  "cycleDays": 28,
  "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.",
  "dueDate": "2026-10-08",
  "gestationalAge": "10w0d",
  "gestationalDays": 70,
  "lmp": "2026-01-01",
  "milestones": {
    "anatomyScanWindowEnd": "2026-06-04",
    "anatomyScanWindowStart": "2026-05-07",
    "conceptionEstimate": "2026-01-15",
    "endFirstTrimester": "2026-04-02",
    "endSecondTrimester": "2026-07-09",
    "fullTermEnds": "2026-10-21",
    "fullTermStarts": "2026-09-17"
  },
  "notChecked": [
    "ultrasound dating, which supersedes this estimate when they differ by more than about a week",
    "irregular cycles, recent hormonal contraception or conception date uncertainty",
    "…2 more"
  ],
  "reasons": [
    "Naegele's rule: LMP + 280 days (40 weeks), adjusted by cycle length minus 28.",
    "Only about 1 in 25 babies arrive on the estimated date; term is 37 to 42 weeks.",
    "…1 more"
  ],
  "source": "computed locally",
  "summary": "Due 2026-10-08 (280 days from LMP). On 2026-03-12: 10 weeks 0 days, first trimester.",
  "trimester": "first trimester",
  "verdict": "COMPUTED"
}

# bash or zsh: see the payment challenge. Nothing is charged.
curl -sS -g -i 'https://fitness-calc.x402tookit.com/due-date?asOf=2026-03-12&lmp=2026-01-01'

# 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://fitness-calc.x402tookit.com/due-date?asOf=2026-03-12&lmp=2026-01-01' \
  | 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%2Ffitness-calc.x402tookit.com%2Fdue-date
const res = await pay("https://fitness-calc.x402tookit.com/due-date?asOf=2026-03-12&lmp=2026-01-01");
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://fitness-calc.x402tookit.com/due-date?asOf=2026-03-12&lmp=2026-01-01")
    print(res.status_code, res.text)