Bulk WHOIS API for Thousands of Domain Lookups

const API_KEY    = 'YOUR_API_KEY';
const RATE_LIMIT = 40; // req/min — Pro:40, Ultra:60, Scale/Mega:100, Atlas:900

const domains = ['example.com', 'github.com', 'google.com'];

const sleep = (ms) => new Promise((r) => setTimeout(r, ms));

async function whoisLookup(domain, retries = 3) {
  const url = `https://whoisjson.com/api/v1/whois?domain=${encodeURIComponent(domain)}`;

  for (let attempt = 1; attempt <= retries; attempt++) {
    const res = await fetch(url, {
      headers: { Authorization: `TOKEN=${API_KEY}` },
    });

    if (res.status === 429) {        // rate-limited — back off
      await sleep(2 ** attempt * 1000);
      continue;
    }
    if (!res.ok) throw new Error(`HTTP ${res.status} for ${domain}`);
    return res.json();
  }
  throw new Error(`${domain}: exceeded retry limit`);
}

async function bulkWhois(domains) {
  const results = [];
  const interval = 60_000 / RATE_LIMIT; // ms between requests

  for (const domain of domains) {
    const t0 = Date.now();

    try {
      const data = await whoisLookup(domain);
      results.push({ domain, data });
      console.log(`[ok] ${domain}  registered=${data.registered}`);
    } catch (err) {
      results.push({ domain, error: err.message });
      console.error(`[err] ${err.message}`);
    }

    const elapsed = Date.now() - t0;
    if (elapsed < interval) await sleep(interval - elapsed);
  }

  return results;
}

bulkWhois(domains).then((r) =>
  console.log(`Done: ${r.length} lookups`)
);

{
  "name": "example.com",           // queried domain, normalized
  "registered": true,               // false when domain is unregistered
  "source": "rdap",                 // "whois" | "rdap"

  "created": "1995-08-14T04:00:00Z",
  "changed": "2023-08-14T07:01:31Z",
  "expires": "2024-08-13T04:00:00Z",

  "age": {                          // only when source = "rdap"
    "days": 10484,
    "months": 345,
    "years": 28,
    "isNewlyRegistered": false,     // true when created <= 30 days ago
    "isYoung": false                // true when created <= 365 days ago
  },

  "expiration": {                   // only when source = "rdap"
    "daysLeft": 109,
    "isExpiringSoon": false,
    "isExpired": false
  },

  "status": [                       // EPP status codes
    "clientDeleteProhibited",
    "clientTransferProhibited"
  ],

  "nameserver": [
    "a.iana-servers.net",
    "b.iana-servers.net"
  ],

  "registrar": {
    "name": "ICANN",
    "url": "https://www.icann.org"
  },

  "contacts": {                     // null when privacy-shielded
    "owner": [{ "name": "...", "email": "...", "country": "..." }],
    "admin":  [{ "name": "...", "email": "..." }],
    "tech":   [{ "name": "...", "email": "..." }]
  },

  "dnssec": "signedDelegation",
  "parsedContacts": true,
  "whoisserver": "whois.iana.org"   // WHOIS server queried
}