[ Technical ]

What Is RDAP and Why It Replaced WHOIS

The technical shift from legacy WHOIS to the modern Registration Data Access Protocol.

· · 7 min read

What Is RDAP and Why It Replaced WHOIS

BatchDomain uses RDAP — the Registration Data Access Protocol — rather than legacy WHOIS. Here's what that means and why it matters.

The Problem With WHOIS

WHOIS is a 40-year-old protocol designed for a simpler internet. Its problems:

  • No standard response format — every registrar returned data differently
  • No authentication or access control
  • Bulk scraping led to massive spam/abuse problems
  • GDPR conflicts — personal data was exposed publicly

By the late 2010s, WHOIS was providing redacted data with no standard structure, making automated parsing unreliable.

Enter RDAP

RDAP (RFC 7480–7484, 2015) was designed as a proper replacement:

  • JSON responses — machine-readable, consistent structure
  • HTTPS — encrypted, authenticated access
  • Bootstrapped via IANA — a central JSON file maps TLDs to their RDAP server URLs
  • Access tiers — registrars can implement auth for full data while returning public subsets for anonymous queries

How BatchDomain Uses RDAP

  1. On first run, we fetch IANA's bootstrap file (https://data.iana.org/rdap/dns.json) — this maps every TLD to its RDAP base URL
  2. For each domain, we construct a query: {rdapBase}domain/{fqdn}
  3. A 404 means the domain is available (no record exists)
  4. A 200 means it's registered — we parse registrar, dates, nameservers, and EPP status from the JSON

This all runs in your browser. No proxy, no server, no rate limit imposed by us.

RDAP Availability by TLD

RDAP coverage is now near-universal for gTLDs and most ccTLDs. Some older ccTLDs still only offer WHOIS. The IANA bootstrap file omits TLDs without RDAP support — BatchDomain will report "no RDAP server" for those and skip them.