WHOIS lookup: who owns a domain?
Who is behind a website? With WHOIS you can look up the registration details of a domain name. Handy if you want to contact the owner, want to check whether a domain is for sale, or want to investigate who is behind a suspicious site.
What is WHOIS?
WHOIS (pronounced "who is") is a public database of domain name registration details. Every time someone registers a domain, data is stored:
- Name of the registrant (owner)
- Contact details (address, phone, email)
- Registration date
- Expiry date
- Nameservers
- Registrar (where the domain is registered)
How do you look up WHOIS data?
There are various ways:
Online WHOIS tools
- SIDN WHOIS (sidn.nl/whois) - for .nl domains
- ICANN Lookup (lookup.icann.org) - for all extensions
- who.is - a popular general tool
Through the terminal (Linux/Mac)
whois example.nlWHOIS privacy: why do I not see any data?
These days you often do not see all the data. That is because of:
GDPR
Since 2018 many registrars have hidden personal data due to privacy legislation. You then see "REDACTED FOR PRIVACY" or similar text.
WHOIS privacy service
Some registrars offer a service in which their data is shown instead of the owner's. At Theory7 you can enable WHOIS privacy for free for supported extensions.
.nl opt-out
For .nl domains you can set an "opt-out" through SIDN so that your personal data is not publicly visible. Only your name (or company name) and email address then remain visible.
What can and cannot you see?
| Data | .nl domain | Other extensions |
|---|---|---|
| Registrant name | Usually visible | Often hidden |
| Full address | Hidden (opt-out) | Often hidden |
| Email address | Visible or proxy | Often a proxy address |
| Registration date | Visible | Visible |
| Expiry date | Visible | Visible |
| Nameservers | Visible | Visible |
What do you use WHOIS for?
- Buying a domain: check who the owner is so you can make contact
- Availability: see when a domain expires
- Investigation: who is behind a spam/phishing site?
- Legal cases: gathering evidence in the case of trademark infringement
- Due diligence: check the history of a domain before purchase
Managing your own WHOIS data
As a domain owner you can usually:
- Update data through your registrar
- Enable privacy (if available)
- For .nl: set an opt-out through SIDN
Tip: keep your contact details current. An outdated email address can cause problems with domain transfers or renewal reminders.
Frequently asked questions
Can I register a domain completely anonymously?
Not really. Your registrar must have your real data (a legal requirement). You can use WHOIS privacy so that it is not publicly visible.
Why is WHOIS important for security?
WHOIS helps identify the owners of malicious sites and is a tool for researchers and authorities.
Can I buy an expired domain?
Yes, if a domain expires and the owner does not renew, it becomes available. Through WHOIS you can check the expiry date.
Checking a domain
Changing WHOIS data
You can always change your WHOIS data through your domain registrar. This is important if you move, change email address, or your company details change. Keep your data current, as an unreachable email address can cause problems with domain renewals or transfers.
WHOIS for different extensions
The WHOIS rules differ per extension:
- .nl: SIDN offers privacy by default. Only limited data is public.
- .com/.net/.org: public by default, WHOIS privacy possible through the registrar.
- .eu: after the GDPR, largely shielded for natural persons.
WHOIS for research
WHOIS is a useful tool for various purposes:
Checking whether a domain is for sale
If a domain is registered, you can sometimes find out through WHOIS who the owner is. This way you can make contact to ask whether the domain is for sale.
Checking trustworthiness
For questionable websites you can check through WHOIS when the domain was registered, where the owner is located, and whether the data is complete. Very new domains with hidden data can be a red flag.
Finding technical information
WHOIS also shows the nameservers of a domain. This is handy for troubleshooting or to see with which provider a website is hosted.
WHOIS privacy considerations
Do you want privacy or rather openness? Companies often show their data for transparency and trust. Private individuals and small entrepreneurs more often choose WHOIS privacy to prevent spam and unwanted contact attempts. Both choices are valid, so decide what suits your situation.
WHOIS is a useful tool for everyone who works with domains. Whether you are looking for the owner of an interesting domain, checking the reliability of a website, or want to protect your own data, knowledge of WHOIS helps you further. Keep your own WHOIS data current and consider privacy protection if you would rather not have your personal data public.
WHOIS information is a valuable resource for domain research. Whether you want to buy a domain, contact the owner or investigate trademark infringement, WHOIS gives you the information you need. Do keep in mind that privacy protection is becoming increasingly common, so contact details are not always visible. Use the available information responsibly.
WHOIS provides insight into domain ownership. Use it responsibly and respect the privacy of domain owners.
WHOIS remains a useful tool for domain research, despite the increasing privacy protection in registrations.
Use WHOIS responsibly for legitimate research.
Want to see whether a domain name is available? Check the availability here, and you will immediately see whether it is free and what it costs.
WHOIS lookup: what information can you find?
When you perform a WHOIS lookup, you can find various types of information. The available data depends on the extension and the privacy settings.
| Data category | .nl domain | .com domain | With WHOIS privacy |
|---|---|---|---|
| Registrant name | Not public | Visible | Hidden |
| Registration date | Visible | Visible | Visible |
| Expiry date | Visible | Visible | Visible |
| Nameservers | Visible | Visible | Visible |
| Registrar | Visible | Visible | Visible |
| Email address | Not public | Visible | Hidden |
| Phone number | Not public | Visible | Hidden |
| Address details | Not public | Visible | Hidden |
WHOIS lookup for different purposes
A WHOIS lookup of a domain is useful in various situations. Below are the main applications:
- Buying a domain: check who the owner is and make contact to make an offer
- Trademark research: check whether a domain name has already been registered by another company
- Spam research: find out who is behind a suspicious website or email
- Technical research: look up the nameservers and hosting provider of a website
- Checking the expiry date: discover when a domain becomes available if you want to register it
- Competitor analysis: research when competitors registered their domains
Want to check whether a domain name is available? Use our domain name checker for a quick availability check.
Frequently asked questions about a WHOIS lookup
Is a WHOIS lookup legal?
Yes, WHOIS is a public register and looking up data is completely legal. Since the introduction of the GDPR, however, personal data of European registrants is often shielded.
Why do I not see an owner for some domains?
This is because of WHOIS privacy protection. Registrars offer this service to shield personal data. For .nl domains personal data is not public by default, in line with the policy of SIDN and the GDPR.
How often is WHOIS data updated?
WHOIS data is usually updated within 24 hours after changes with the registrar. Some registrars process changes faster, within a few minutes.
Can I still find the owner behind an anonymized domain?
For anonymized domains you can submit a request through the registrar to make contact with the owner. In legal disputes access to the data can be enforced through a court order. Read more about domain names and registration at Theory7.
WHOIS lookup: tools and resources
There are various tools available to perform a WHOIS lookup. Each tool has its own advantages and disadvantages.
| Tool | Type | Free | Extensive info | Bulk lookup |
|---|---|---|---|---|
| SIDN (for .nl) | Official register | Yes | Limited (GDPR) | No |
| ICANN Lookup | Official register | Yes | Yes | No |
| Whois.domaintools.com | Commercial | Limited | Very extensive | Paid |
| who.is | Free | Yes | Good | No |
| Linux/Mac terminal | Command line | Yes | Complete | Through scripting |
Interpreting WHOIS data
When you perform a WHOIS lookup, you get a lot of information back. Here is how to interpret the most important fields:
- Registrant: the owner of the domain. With privacy protection you see the data of the proxy service here.
- Creation Date: when the domain was first registered. Older domains often have more authority.
- Expiry Date: when the registration expires. Check whether there is still time if you want to buy the domain.
- Registrar: the company through which the domain is registered. This is the party you have to approach for a transfer.
- Name Servers: the DNS servers that serve the domain. This often tells you who provides the hosting.
- Status codes: codes such as "clientTransferProhibited" indicate that the domain is protected against unauthorized transfer.
Tip: combine WHOIS data with a domain name check to get a complete picture of the availability and ownership of a domain name.
WHOIS and the GDPR
Since May 2018 WHOIS data of European domain owners has been largely shielded due to the GDPR. This means that personal data such as name, address and phone number is no longer publicly visible by default. Registrars are obliged to protect this information, but often offer a contact form with which you can send a message to the domain owner.
WHOIS lookup for a domain purchase
A WHOIS lookup is indispensable when you want to buy an existing domain. By analyzing the WHOIS data you can gather valuable information before you make an offer:
- Registration date: a domain that has been registered for many years often has more value due to built-up domain authority
- Expiry date: if the domain expires soon, the owner may be willing to sell it more cheaply
- Registrar information: some registrars offer a "make offer" function with which you can make an offer directly
- Historical WHOIS: services such as DomainTools show previous owners and changes, which gives insight into the history of the domain
Always combine WHOIS data with tools such as Archive.org (the Wayback Machine) to see how the domain was used before. A domain with a clean history is worth more than a domain that was previously used for spam. Check the availability directly through our domain name checker.
WHOIS lookup: advanced applications
A WHOIS lookup of a domain offers more possibilities than just viewing the owner. Professionals use WHOIS data for various purposes that are essential in domain management and security.
WHOIS for domain research
Before you register a domain name, it is wise to research the WHOIS history. This lets you discover whether the domain has been used before and for what purpose. A domain with a clean history is more valuable than a domain that was previously used for spam or malware. Tools such as DomainTools and the Wayback Machine help you research the full history of a domain name, including previous owners and website content.
Setting up WHOIS monitoring
For companies that take their online presence seriously, WHOIS monitoring is a valuable tool. You can set up alerts that warn you when changes are made to the WHOIS data of your domains or when domains are registered that resemble your brand name. This helps detect cybersquatting and phishing attempts early that could harm your brand.
Comparison of WHOIS tools
| Tool | Cost | Features | Suitable for |
|---|---|---|---|
| SIDN WHOIS | Free | Only .nl domains | Dutch domains |
| ICANN Lookup | Free | All extensions | General research |
| DomainTools | Paid | Historical WHOIS, monitoring | Professionals |
| WhoisXML API | Paid | API access, bulk queries | Developers |
WHOIS lookup and privacy: what you need to know
With the introduction of the GDPR, the rules around a WHOIS lookup have changed considerably. Understand your rights and obligations as a domain owner.
Impact of the GDPR on WHOIS
Since the introduction of the GDPR in 2018 many registrars have moved to shielding personal WHOIS data. For .nl domains SIDN shows only the name of the registrar and the registration date. Personal data of the domain owner is no longer publicly visible. This is an important privacy protection, but it can complicate research into domain ownership when this is needed for legal procedures.
WHOIS privacy services
For generic domains such as .com and .net many registrars offer a WHOIS privacy service. This shows the data of the registrar or a proxy service instead of your personal information. This protects you against spam, identity theft and unwanted marketing. With most reliable hosting providers this service is included for free with your domain name registration.
When is WHOIS data visible?
Despite privacy protection, there are situations in which WHOIS data has to be released. In legal disputes a judge can oblige the registrar to release the data of the domain owner. Also in cases of suspected misuse of a domain for illegal activities, law enforcement agencies can gain access to the full WHOIS information through the registrar.
WHOIS lookup: practical applications and frequently asked questions
A WHOIS lookup has various practical applications that go beyond simply checking ownership. Below we discuss common scenarios and answer frequently asked questions.
WHOIS for business purposes
Companies use WHOIS information for various business purposes. Marketers check the owner of a competitor's domain. Legal departments identify trademark infringers. Sales teams look for contact details of potential customers. Web developers check domain availability for their clients. IT security teams investigate suspicious domains that are used in phishing attacks. In all these cases WHOIS is the starting point for further research.
Frequently asked questions about WHOIS
- Is it legal to use WHOIS information? Yes, WHOIS information is publicly available. Using it for commercial purposes such as unwanted marketing is, however, often not allowed under the registrar's terms.
- Why do I not see any contact details? Since the GDPR, personal data is shielded with most registrars. You only see the name of the registrar and the registration date.
- How do I check whether a domain expires soon? The WHOIS data shows the expiry date of the domain. After expiry the domain usually becomes available again for registration by third parties after a waiting period of 40 to 90 days.
- Can I see who previously owned a domain? With historical WHOIS tools such as DomainTools you can retrieve previous owners and registration dates, provided this data is available in their database.
Checking domain availability
WHOIS is the most reliable way to check the availability of a domain name. Some domain registration websites register domains you search for if they seem interesting, a practice called domain front running. By performing a WHOIS query directly, you check availability without this risk. Use the official WHOIS databases of the relevant registries for the most current information.
Theory7 is a SIDN registrar and EURid registrar. As an accredited registrar you register domain names directly at the source, without an intermediary. This gives you faster processing times and full control over your domain management.
WHOIS lookup: summary tips for daily use
With the right knowledge and tools, a WHOIS lookup becomes a valuable part of your daily online work.
A quick WHOIS check routine
Make it a habit to check WHOIS information for various activities. Check the owner and registration date before you buy a domain from a third party. Verify that your own domain details are correct and current at every renewal. Check the expiry date of your customers' domains if you offer web services. Investigate suspicious domains that appear in phishing emails through a WHOIS lookup before you click on links. These simple checks take only a few seconds but can save you a lot of problems.
Keeping WHOIS information up to date
Make sure your own WHOIS information is always current. Outdated contact details can cause you to miss important notifications about your domain, such as renewal reminders or dispute procedures. Check annually whether your name, address, phone number and email address are correct with your registrar. Update your data immediately after a move, name change or takeover of your company. Always keep access to the email address linked to your domain registration, because this address is used for important communication about your domain.
WHOIS lookup: privacy and data protection
In a WHOIS lookup, privacy plays an increasingly large role. Since the introduction of the GDPR, many registrars offer WHOIS privacy protection by default, so that personal data of domain owners is no longer publicly visible. This means a WHOIS lookup often shows limited information for European domains. For .nl domains SIDN shows only the name of the registrar and the registration date, but not the personal data of the owner. You can, through the registrar, submit a request to contact the domain owner without directly receiving their data.
WHOIS and domain disputes
WHOIS information plays an important role in domain disputes and brand protection. The registration date from the WHOIS database can prove who first claimed a domain name. In dispute procedures through WIPO or the Czech Arbitration Court, WHOIS data is used as evidence to establish ownership and intent.
Sources and references
- SIDN - Stichting Internet Domeinregistratie Nederland (sidn.nl)
- ICANN - Internet Corporation for Assigned Names and Numbers (icann.org)
- Autoriteit Persoonsgegevens - GDPR information (autoriteitpersoonsgegevens.nl)
