Validate IBAN format, calculate MOD-97 check digits

curl -X POST 'https://app.castomapi.com/v1/verify/iban' \
  -H 'x-api-key: <your-api-key>' \
  -H 'Content-Type: application/json' \
  -d '{"iban": "PL61 1090 1014 0000 0712 1981 2874"}'

const res = await fetch('https://app.castomapi.com/v1/verify/iban', {
  method: 'POST',
  headers: { 'x-api-key': '<your-api-key>', 'Content-Type': 'application/json' },
  body: JSON.stringify({"iban": "PL61 1090 1014 0000 0712 1981 2874"})
});
const data = await res.json();
console.log(data);

import { request } from 'node:https';

// Node 18+ has fetch built in
const res = await fetch('https://app.castomapi.com/v1/verify/iban', {
  method: 'POST',
  headers: { 'x-api-key': '<your-api-key>', 'Content-Type': 'application/json' },
  body: JSON.stringify({"iban": "PL61 1090 1014 0000 0712 1981 2874"})
});
const data = await res.json();
console.log(data);

import requests

res = requests.post(
    'https://app.castomapi.com/v1/verify/iban',
    headers={'x-api-key': '<your-api-key>'},
    json={"iban": "PL61 1090 1014 0000 0712 1981 2874"},
    timeout=30,
)
print(res.json())

<?php
$ch = curl_init('https://app.castomapi.com/v1/verify/iban');
curl_setopt_array($ch, [
    CURLOPT_CUSTOMREQUEST => 'POST',
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_HTTPHEADER => ['x-api-key: <your-api-key>', 'Content-Type: application/json'],
    CURLOPT_POSTFIELDS => json_encode(['iban' => 'PL61 1090 1014 0000 0712 1981 2874']),
]);
$data = json_decode(curl_exec($ch), true);
print_r($data);