WHOIS Lookup: Search for the owner of a domain, IP or email address

Why use WHOIS Lookup?

• Ample reach across TLDs

  WHOIS Lookup contains the records of over 374 million currently active domains spanning more than 7,596 generic (gTLDs) and country-code top-level domains (ccTLDs).

• Readily available and easy to use

  WHOIS Lookup reports are parsed and normalized so professionals can easily access and make sense of the information they provide. Query results are available in seconds for faster decision-making.

• Shareable results

  WHOIS Lookup’s domain search query results come with custom URLs that users can readily share with relevant parties with just a few clicks.

• Optimized for RDAP and WHOIS

  We continuously update our records and query both WHOIS and RDAP protocols to ensure uninterrupted access to the latest domain ownership data.

Frequently Asked Questions

What is a WHOIS lookup?

A WHOIS lookup is a search query that pulls up the latest registration details of a domain name or IP address. It queries the WHOIS database and returns information like who registered the domain, when, and which company manages it.

Originally, these lookups relied on the WHOIS protocol, however, lately, many lookups run on a newer protocol called Registration Data Access Protocol (RDAP) instead of the classic WHOIS, since ICANN now requires all gTLDs to support RDAP. The result is similar — a report on who registered a particular domain or IP. Since the process of obtaining domain registration information has been historically known as a WHOIS lookup, the industry continues to refer to it that way, even though, in many cases, it is in fact an RDAP lookup.

What information can a WHOIS lookup show?

The exact fields you get depend on the lookup protocol, the registry, and registrar.

A typical WHOIS record includes the domain's registrar, its creation and expiration dates, the nameservers it uses, and the registrant's contact details, if they're not hidden. For IP addresses, you'll usually see the network range, the organization it's assigned to, and contact info for that network. The exact fields can vary a bit depending on the registry or registrar.

RDAP responses follow RFC 9083, which defines the structure for JSON-based registration data. ICANN's RDAP Profile builds on that standard and spells out which fields gTLD registries and registrars must return, which are:

• Domain name and registry data: The domain name itself, its registry domain ID, and status codes that show things like whether the domain is locked or pending transfer.
• Registrar information: The registrar's name, IANA ID, and abuse contact.
• Key dates: When the domain was created, when it was last updated, and when it expires.
• Nameservers: The DNS servers used to resolve the domain.
• Registrant, admin, and technical contacts: Names, organizations, and contact details for the domain, if they aren't redacted.
• DNSSEC status: Whether DNSSEC is turned on for the domain.

Why are some WHOIS details hidden or redacted?

Privacy laws such as GDPR prompted ICANN to adopt policy — originally the 2018 Temporary Specification, now ICANN's permanent Registration Data Policy (in full effect since August 21, 2025) — requiring registrars to redact registrant names, email addresses, and phone numbers by default. Some registrars offer domain privacy protection services that replace the registrant’s real contact information with a proxy address.

If you need to check what a record looked like before redaction took effect, tools like our WHOIS History can pull up older, unredacted data, if it was ever available.

Can I use WHOIS Lookup to check if a domain is available?

Yes, but it’s not the most convenient way of doing that.

When you run a WHOIS query for an unregistered domain, our WHOIS lookup tool will return a record showing the parsed domain name, the extension, and a timestamp, but the registration fields will be empty, and you'll see a MISSING_WHOIS_DATA error instead of registrar or contact info.

The classic whois command and ICANN’s WHOIS lookup tool behave similarly. Depending on the registry operator, these tools return a “Domain not found,” “No registry RDAP server was identified for this domain,” or “The requested domain was not found in the Registry or Registrar's RDAP server” error message.

We have a dedicated tool called the Domain Availability API built specifically for checking domain availability — it’s fast, the responses are much smaller, and overall it’s much better suited for that purpose.

What is the difference between WHOIS and RDAP?

WHOIS and RDAP are both protocols used to look up domain registration data.

WHOIS is an older protocol that returns plain text, and its format can vary from one registrar to the next.

RDAP is the newer standard that ICANN now requires for gTLDs. It returns structured JSON data instead of freeform text, which makes it easier for software to parse consistently.

RDAP also supports differentiated access, meaning some data can be shown to certain requestors and hidden from others, a feature WHOIS never had. You can read more in our full breakdown of WHOIS vs. RDAP.

How does WhoisXML API’s WHOIS lookup switch between WHOIS and RDAP?

Our WHOIS lookup tool includes a protocol selector, so you can choose RDAP, WHOIS, or Auto. Auto mode — which is the default one — picks whichever protocol is available and appropriate for the domain you're searching, so you get a result without having to know in advance which one applies.

What is the difference between a WHOIS lookup and a DNS lookup?

A WHOIS lookup tells you who owns a domain and how to reach the registrar. A DNS lookup tells you how that domain is configured to work online, showing records like the IP address it points to or its mail servers.

There's some overlap, though. Nameservers appear in both a WHOIS record and a DNS lookup, since they're part of the domain's registration data and control how its DNS is resolved.

Can I perform a WHOIS lookup for an IP address?

Yes. An IP WHOIS lookup returns the organization the IP address is registered to, along with contact details, usually maintained by a regional internet registry like ARIN or RIPE rather than a domain registrar.

If you need the specific network range or block details, you can try our IP Netblocks API.

Can I run WHOIS lookups in bulk?

Yes, but not through the standard WHOIS Lookup tool, which is built for one-at-a-time searches. For bulk lookups, our Bulk WHOIS API lets you query up to 500,000 domains in a single request.

How do I do a WHOIS lookup?

The easiest way is through our WHOIS Lookup tool. Just type in a domain name or IP address and hit enter, and you'll get a readable, real-time report with registrar, dates, nameservers, and contact details where available.

If you'd rather work from a terminal, there's also the native whois command built into most operating systems, though it has some quirks and limitations we cover in our WHOIS command guide.

If you want to use WHOIS lookups as a part of an automated process, it’s best to use the WHOIS API to get standardized output and avoid rate limiting.

What are some common use cases for a WHOIS lookup?

• Security investigations: Checking a domain for signs of phishing or fraud, such as suspicious registration patterns or malicious nameservers.
• Due diligence: Verifying who owns a domain before a business partnership or acquisition.
• Domain investing: Domainers use WHOIS lookups to check registration and expiration dates and other domain insights to find opportunities.
• Legal and brand protection: Tracking down infringing domains and identifying who registered them.

Can a WHOIS domain lookup be incorrect?

It can, but the reason usually comes down to the data itself, not the lookup tool. WHOIS records depend on what the registrant entered when they signed up, so if someone moved or changed their phone number and never updated their registrar, the record goes stale. So a WHOIS lookup is only as accurate as the information behind it.

ICANN requires registrars to investigate and correct inaccurate data, and you can file a complaint with ICANN if you spot something wrong.

If a record looks outdated or you want to confirm when a change happened, our WHOIS History lookup tool lets you look back at a domain's past registration data.