WHOIS is a widely used query and response protocol that provides information about registered domain names, IP address blocks, and autonomous systems. Originally defined in RFC 3912, the WHOIS protocol allows anyone to look up ownership and registration details for a domain by querying a WHOIS database maintained by domain registrars and regional internet registries. When you perform a WHOIS lookup, the query is routed to the appropriate WHOIS server based on the top-level domain (TLD), and the server returns a structured text response containing registration data.
A WHOIS record typically contains several key pieces of information about a domain registration. These include the registrant (the person or organization that owns the domain), the registrar (the company through which the domain was registered), important dates such as the creation date, expiration date, and last updated date, as well as the domain's name servers and status codes. Domain status codes like clientTransferProhibited or serverDeleteProhibited indicate various locks and protections placed on the domain. ICANN (the Internet Corporation for Assigned Names and Numbers) requires that registrars collect and maintain accurate WHOIS information for generic top-level domains (gTLDs) as part of the domain registration agreement.
Many domain registrars offer WHOIS privacy protection (also called domain privacy or proxy registration) as an add-on service that replaces the registrant's personal contact details with those of a privacy proxy service. This helps protect domain owners from spam, unwanted solicitation, and identity theft. With the introduction of the GDPR in 2018, many registrars began redacting personal data from WHOIS records by default for domains registered by individuals in the European Union.
WHOIS lookups serve many practical purposes. Security researchers use WHOIS data to investigate phishing domains, track malicious infrastructure, and identify patterns across registrations. Businesses use it to monitor brand-infringing domains or research potential domain purchases. Network administrators rely on WHOIS to identify the owners of IP addresses involved in abuse incidents. Our free WHOIS lookup tool lets you instantly query domain registration information, helping you verify domain ownership, check expiration dates, and investigate domain history without needing to use command-line tools.