WHOIS
The public lookup that tells you who registered a domain name and when.
WHOIS is a decades-old system for asking "who is behind this domain or IP address?". Type a domain into a WHOIS lookup and you get its registration record: which registrar it was bought through, when it was created, when it expires, which name servers it uses, and sometimes who the owner is.
It is a daily tool for many people. Someone checking whether a domain is free, a security analyst looking at a suspicious link (a phishing site registered three days ago is a red flag), a company chasing a trademark copycat, or a network engineer finding who runs a block of IP addresses, which regional internet registries also publish this way.
What it shows has changed. Since privacy laws like GDPR took effect in 2018, personal names, emails and phone numbers are usually hidden or replaced by a privacy service. The protocol is also being replaced by RDAP, which returns the same kind of data in a structured JSON format with better access control; for generic domains like .com, ICANN has made RDAP the official source since 2025. Most lookup websites already query RDAP behind the scenes, so to a user it looks the same.
Keep in mind
- Looks up registration data for a domain or IP address.
- Shows registrar, creation and expiry dates, and name servers.
- Owner contact details are usually redacted since GDPR (2018).
- RDAP, a JSON-based successor, is replacing it.
