What Reverse WHOIS Used to Do
A normal WHOIS lookup takes a domain and shows its registration details. Reverse WHOIS works the other way: you enter an owner’s name, email address or company and get a list of domains registered with those details. For years it was a standard tool for brand protection, fraud investigations and domain research.
What Changed in 2018
When the EU’s General Data Protection Regulation (GDPR) took effect in May 2018, registries and registrars began to redact personal data from public WHOIS output. Names, email addresses, phone numbers and street addresses of registrants were replaced by placeholders such as “REDACTED FOR PRIVACY” or by anonymized forwarding addresses. Many registrars applied this worldwide, not only to EU customers, and privacy services had already hidden many owners before that.
Since then, generic top-level domains have also moved from the old WHOIS protocol to RDAP (Registration Data Access Protocol), which returns structured data but follows the same redaction rules.
What Is Still Public
- Registrar, creation and expiry dates, status codes — always visible. Use our WHOIS Lookup.
- Nameservers — always visible, and very useful for finding related domains.
- Organization, state and country — often shown when the registrant is a company and the registrar publishes them.
- Some country-code domains follow their own rules and may still publish more data.
- Historical records — commercial databases keep WHOIS data collected before 2018, which still links older domains to their owners.
Practical Alternatives for Finding Related Domains
Shared Infrastructure
Domains run by the same owner often share servers. Check which domains use the same:
- web server address — Reverse IP Lookup;
- nameservers — Reverse NS Lookup (most useful with custom or small DNS providers);
- mail server — Reverse MX Lookup, see what reverse MX shows.
Certificates
A single TLS certificate can cover several domains. Certificate Transparency logs show which names were issued together. See How to find subdomains for how CT search works.
Shared Identifiers in Pages
Websites operated together often reuse the same analytics or advertising account IDs, contact details or legal notices. These public clues can connect domains without any WHOIS data.
Formal Disclosure Requests
For legitimate purposes such as legal claims or abuse investigations, the redacted data can be requested from the registrar. ICANN also runs a request service for generic top-level domains that forwards such requests to participating registrars. Disclosure is not guaranteed.
Is a Paid Reverse WHOIS Service Worth It?
Paid services are mainly valuable for their historical data and for the minority of domains that still publish owner details. For current registrations of private individuals they return little. Combining the free infrastructure methods above usually gives a faster, more reliable picture.