Whois lookup for IP addresses and domains
Whois reveals public registration data: for a domain — the registrar, statuses and dates; for an IP address — the network, organization and abuse contact. Queries are made over RDAP to the official registries.
What is Whois
Whois ("who is this") is a public database of registered domains and allocated IP networks. For a domain you can see the registrar, creation and expiration dates, statuses and DNS servers; for an IP address — the owner of the network (usually an ISP or a data center), the network range and the abuse contact.
The modern version of the protocol is RDAP (Registration Data Access Protocol), which serves machine-readable JSON. We query the official registries directly, so the data matches what the registrar sees.