Who.is provides **Domain Name Information Lookup** for domain names, websites, and IP tools.

Search WHOIS, RDAP, DNS, and nameserver information for any domain name. Instantly look up registration data, contact details, nameservers, DNS records, and more for any domain name or IP address using WHOIS and RDAP protocols.

- **WHOIS Lookup**: Registrant, registrar, and registration dates for any domain.

- **RDAP Lookup**: Structured registration data via the modern WHOIS successor.

- **DNS Records**: A, AAAA, MX, TXT, NS and other records for any domain.

- **Nameserver Lookup**: See which domains a given nameserver hosts.

- **IP Address Lookup**: Ownership and network data for any IPv4 or IPv6 address.

- **Domain History**: How much historical WHOIS/RDAP we hold for a domain.

- **Uptime Check**: Check whether a website is reachable right now.

WHOIS is a widely used internet protocol to query databases storing information about registered users of domain names, IP addresses, and autonomous systems. RDAP (Registration Data Access Protocol) is the modern successor to WHOIS. It provides a standardized, secure, and more structured way to access registration data, often offering richer information and better privacy controls.

Who.is also lists premium services including **Domain History Report** and **Pro Website Monitoring**. The site states it holds **2B+ Historical WHOIS & RDAP snapshots**, with domain data **Since 2007**, and serves **Millions of lookups every month**.