WHOIS Lookup Online
Free Domain Owner Search & Registration Checker
Use our free WHOIS lookup online tool to check domain registration details for any website. This ICANN domain search tool queries authoritative registries via Port 43 and RDAP to reveal domain owner information, registrar details, creation date, expiration date, nameservers, domain status codes like ClientTransferProhibited, and WHOIS privacy status. Supports 25+ TLDs including .ai, .io, .dev, .co, and all major extensions.
Quick Answer: What Is a WHOIS Lookup?
A WHOIS lookup online queries global domain registries to reveal website ownership details including the registrant name, registrar information, creation date, expiration date, nameservers (NS), registry ID, and domain status codes. Due to GDPR domain protection, personal details are often redacted for privacy, but technical and registrar data remains publicly accessible. Our domain owner search tool supports 25+ TLDs and automatically detects WHOIS privacy masking, calculates domain age, and checks domain availability.
Domain Owner Search & Registration Checker
Enter any domain to check domain registration, find website ownership, verify expiry dates, and detect WHOIS privacy status.
Sarah Thompson
Network Intelligence Analyst
Sarah specializes in WHOIS forensics, domain intelligence analysis, IP geolocation data, and ICANN registry compliance. She helps investigators, domain investors, and business owners understand domain ownership structures, registration histories, and privacy implications under GDPR.
View All Articles by Sarah ThompsonWhat Is a WHOIS Lookup Online and What Does It Reveal?
A WHOIS lookup online queries global domain registries to reveal the registration details behind any website address. Think of it as the internet's public property record — every domain registered through ICANN-accredited registrars has a WHOIS record that documents who registered it, when it was created, when it expires, and which nameservers control its DNS.
Our domain owner search tool connects directly to authoritative WHOIS servers via Port 43 — the traditional TCP gateway for registration data. When you check domain registration through our tool, it returns the registrant name (or privacy proxy), registrar information, creation date, expiration date, nameservers (NS), registry ID, domain status codes, and abuse contact details.
According to Wikipedia's article on WHOIS, the protocol dates back to 1982 (RFC 812) and remains one of the oldest continuously used systems on the internet. Despite its age, WHOIS is indispensable for cybersecurity investigations, domain trading, legal enforcement, and business due diligence.
Key Fact: Our WHOIS lookup online tool supports over 25 TLDs including .ai, .io, .dev, .co, .app, .tech, and all major country-code extensions. It automatically follows Thin WHOIS referrals to registrar servers for the most complete data and detects WHOIS privacy masking when present.
How WHOIS Works: Port 43, Thin vs Thick WHOIS, and RDAP
Understanding the technical infrastructure behind a WHOIS lookup online helps you interpret results accurately and know the limitations of the data you receive.
Port 43: The Traditional WHOIS Protocol
When you run a domain owner search, our tool opens a TCP connection to Port 43 on the authoritative WHOIS server for that TLD. It sends the domain name as a plain-text query, and the server responds with unstructured text containing all registration data. This protocol has remained virtually unchanged since 1982, which is both its strength (universal support) and weakness (no standardized format).
Thin WHOIS vs Thick WHOIS
WHOIS servers come in two varieties. Thin WHOIS servers (used by Verisign for .com and .net) only store technical data — registrar name, nameservers, dates, and status codes. To get registrant contact details, our tool automatically follows the referral to the registrar's own WHOIS server. Thick WHOIS servers (used by .org, many ccTLDs) store both technical and registrant data in one location, providing more complete results in a single query.
RDAP: The Modern Replacement
The Registration Data Access Protocol (RDAP) is gradually replacing Port 43 WHOIS. RDAP delivers data in structured JSON format over HTTPS, supports authentication, handles internationalized domain names, and provides better query rate limits management. ICANN mandated RDAP support for all gTLD registries, though many still maintain Port 43 as a fallback. Our tool bridges both protocols for maximum compatibility.
# How our WHOIS lookup works internally:
1. User enters domain: example.com
2. Tool identifies TLD: .com
3. Routes to Verisign server: whois.verisign-grs.com
4. TCP Port 43 query: "example.com\r\n"
5. Thin WHOIS returns registrar referral
6. Tool follows referral to registrar WHOIS server
7. Full data returned → parsed + displayed
# Supported TLD servers include:
.com/.net → whois.verisign-grs.com
.org → whois.pir.org
.io → whois.nic.io
.ai → whois.nic.ai
.dev/.app → whois.nic.google
How to Find the Owner of a Website with WHOIS Privacy
Since GDPR domain protection took effect in 2018, most WHOIS records now show personal details as "Redacted for Privacy" or display a privacy proxy service instead of the actual owner. This WHOIS privacy masking protects domain owners from spam, harassment, and identity theft — but it creates challenges for investigators, buyers, and legal teams.
What WHOIS Privacy Hides
WHOIS privacy services replace the registrant's personal name, address, phone number, and email with generic proxy information. However, they do NOT hide the registrar name, creation date, expiration date, nameservers, domain status codes, or the registrar abuse contact email. Our WHOIS privacy checker automatically detects when privacy services are active.
How to Reach the Actual Owner
Even with privacy enabled, you can still contact the domain owner through the abuse contact email shown in WHOIS results, the privacy proxy forwarding address (most proxy services forward legitimate inquiries), or by submitting a formal request through the registrar's website. For legal proceedings, courts can compel registrars to reveal the actual identity behind WHOIS privacy shields. Check our guide on whether it is legal to trace someone's IP address for related privacy considerations.
Important: Our WHOIS lookup online tool displays whatever the registry returns — including privacy-redacted data. If you see "Redacted for Privacy" or a proxy service name, the domain has WHOIS privacy masking enabled. The registrar abuse contact and technical data (nameservers, dates, status) remain fully visible regardless of privacy settings.
Domain Status Codes Explained: ClientHold to PendingDelete
Every domain in WHOIS has one or more status codes that indicate its current state. Understanding these codes helps you assess domain security, identify expiring domains for purchase, and diagnose website outages.
Active Protection Statuses
- clientTransferProhibited: Registrar lock prevents unauthorized transfers. This is a security feature — a good sign that the domain is protected from hijacking.
- clientDeleteProhibited: Prevents accidental or unauthorized deletion of the domain at the registrar level.
- clientUpdateProhibited: Blocks unauthorized changes to domain records including nameservers and contact information.
- serverTransferProhibited: Registry-level lock, typically applied during dispute resolution (UDRP) proceedings.
Warning and Expiration Statuses
- ClientHold: The registrar has suspended DNS resolution. The website and email stop working. Usually caused by non-payment, legal disputes, or abuse reports.
- RedemptionPeriod: The domain has been deleted by the registrar and enters a 30-day recovery window. The original owner can reclaim it by paying a redemption fee (often $100+).
- PendingDelete: The final 5-day countdown before a domain is released back to the public. Cannot be renewed or recovered. Domain investors monitor this status for "drop catching" opportunities.
Our tool automatically color-codes these status values — green for protective statuses, red for suspended or pending deletion. For domain investors wondering about backorder opportunities, seeing PendingDelete or RedemptionPeriod in WHOIS is the signal to prepare. Check domain IP reputation with our IP Blacklist Checker before acquiring expired domains.
Free Tool to Check Domain Expiry Date and Registrar
Checking domain expiry dates is one of the most common uses of a WHOIS lookup online. Whether you are monitoring your own domains, scouting expiring domains for investment, or verifying a business partner's domain status, our tool provides this data instantly.
Why Expiry Dates Matter
A domain that expires loses DNS resolution — your website goes offline and emails stop working. If you do not renew within the grace period (typically 30-45 days), the domain enters RedemptionPeriod with expensive recovery fees, then PendingDelete, and finally becomes available for anyone to register. Entire businesses have been disrupted because someone forgot to renew a domain.
How Our Tool Helps
Our domain availability checker displays the expiration date with a countdown showing days remaining. Domains expiring within 30 days get a red warning, within 90 days get an amber notice, and beyond 90 days show green. This visual system makes it impossible to miss an upcoming expiry when auditing your domain portfolio.
For deeper investigation into the hosting behind any domain, combine WHOIS with our IP Lookup Tool to see the server's geographic location and ISP, and our Cloud IP Check to identify if the server runs on AWS, Google Cloud, or Azure.
Domain Management Tip: Set your domains to auto-renew and register critical domains for the maximum 10-year period. Use our WHOIS lookup online tool quarterly to verify expiry dates, nameserver configurations, and domain status codes across your entire portfolio.
Find Host of a Website Through WHOIS Data
One of the most practical uses of WHOIS is identifying who hosts a website. The nameservers (NS) field in WHOIS results reveals the DNS provider, which frequently indicates the hosting company.
Reading Nameservers to Identify Hosting
Nameservers follow patterns that identify the provider. For example, nameservers containing "cloudflare" indicate Cloudflare DNS (and likely Cloudflare hosting or proxy). Nameservers with "awsdns" indicate Amazon Route 53. Nameservers containing "digitalocean" point to DigitalOcean hosting. By recognizing these patterns, you can determine a competitor's hosting infrastructure from a single WHOIS query.
| Nameserver Pattern | Provider | Service Type |
|---|---|---|
| *.ns.cloudflare.com | Cloudflare | CDN / DNS / Proxy |
| ns-*.awsdns-* | Amazon Route 53 | Cloud DNS |
| ns*.google.com | Google Cloud DNS | Cloud DNS |
| ns*.digitalocean.com | DigitalOcean | Cloud Hosting |
| dns*.registrar-servers.com | Namecheap | Domain Registrar |
| *.domaincontrol.com | GoDaddy | Hosting / Registrar |
For a complete hosting infrastructure analysis, run a WHOIS lookup to identify nameservers, then use our DNS Lookup Tool to see the actual A records (server IPs), and finally check those IPs with our Reverse IP Lookup to see what other domains share the same server. Our guide on finding any website's server IP covers this workflow in detail.
WHOIS Lookup for .ai and .io Niche Domains
The rise of AI startups and tech companies has made .ai and .io TLDs extremely popular and valuable. Our WHOIS lookup online tool supports both extensions with dedicated authoritative servers.
.ai Domain WHOIS
.ai domains are managed by the government of Anguilla (a British Overseas Territory). WHOIS queries route to whois.nic.ai. Due to the AI industry boom, premium .ai domains now sell for tens of thousands of dollars. Checking WHOIS for .ai domains reveals creation dates — older registrations from before the AI hype often indicate the domain was originally registered for Anguilla-related purposes and may be available for purchase.
.io Domain WHOIS
.io domains are the country-code TLD for British Indian Ocean Territory but are overwhelmingly used by tech startups and developer tools. WHOIS queries route to whois.nic.io. The .io registry provides Thick WHOIS with registrant details when not privacy-protected, making it useful for identifying startup ownership and contact information.
For investigating the technical infrastructure behind these domains, combine WHOIS data with our SSL Certificate Checker to verify their HTTPS configuration and our HTTP Headers Analyzer to inspect server response details.
Who Uses WHOIS and Why: Real-World Use Cases
A WHOIS lookup online serves fundamentally different purposes depending on who is using it. Here are the primary use cases and what each group looks for in WHOIS results.
Cybersecurity Investigators
When a phishing email arrives, the first step is running a WHOIS query on the sender's domain. A domain registered hours ago via a budget registrar with WHOIS privacy masking enabled is an immediate red flag. Investigators cross-reference the creation date, registrar, and nameservers to assess threat level. Our guide on finding domain owners for cyberbullying reports covers the legal workflow.
Domain Investors
Domain flippers use WHOIS to find domains approaching expiration, identify the registrar for transfer negotiations, assess domain age (older = more SEO authority), and detect PendingDelete status for drop-catching opportunities. Our tool's automatic domain age calculation and expiry countdown make this research instant.
Business Due Diligence
Before signing contracts, partnerships, or investments, verifying that a company actually owns its claimed domain is basic due diligence. A website ownership lookup reveals whether the domain is properly registered, how long the company has held it, and whether it is secured with proper status locks. Read about what information websites can see from your IP for broader online transparency context.
Legal and Trademark Enforcement
WHOIS provides the registrar abuse contact needed for DMCA takedowns, trademark infringement notices, and UDRP (Uniform Domain-Name Dispute-Resolution Policy) proceedings. Even with privacy enabled, the abuse contact email is always visible, ensuring a legal communication channel exists.
The Domain Lifecycle: From Registration to PendingDelete
Understanding the full domain lifecycle helps you interpret WHOIS status codes correctly and identify opportunities. Every domain passes through these stages.
- Available / Unregistered: The domain has no active registration. WHOIS returns "No Match" or "Not Found." Our tool automatically detects this as an available domain.
- Active / Registered: The domain is claimed and operational. WHOIS shows creation date, expiry date, and active nameservers. Status typically includes ClientTransferProhibited for security.
- Auto-Renew Grace Period (0-45 days): The expiry date has passed but the registrar holds the domain. The owner can still renew at normal price. Website and email may stop working.
- Redemption Period (30 days): The registrar has deleted the domain. Recovery requires a redemption fee ($80-$200+). WHOIS shows RedemptionPeriod status.
- Pending Delete (5 days): Final countdown. The domain cannot be recovered and is scheduled for public release. WHOIS shows PendingDelete status. Drop-catching services compete to register it the moment it releases.
Our WHOIS lookup online tool color-codes these statuses automatically — making it easy to instantly identify where a domain sits in its lifecycle. For checking if your domain's IP has any reputation issues, use our IP Blacklist Checker alongside WHOIS verification.
Complete Domain Intelligence Audit Checklist
Combine WHOIS data with our other tools for a comprehensive domain and server audit.
- Step 1: Run a WHOIS lookup online above to check domain registration, ownership, and expiry status.
- Step 2: Use our DNS Lookup Tool to verify A records, MX records, TXT records (SPF/DKIM/DMARC), and nameservers.
- Step 3: Check the server IP with our IP Lookup Tool for geographic location and ISP details.
- Step 4: Run a Reverse IP Lookup to find other domains hosted on the same server.
- Step 5: Verify SSL configuration with our SSL Certificate Checker.
- Step 6: Check if the domain's IP is listed on any IP Blacklists.
- Step 7: Verify the domain's email configuration with our Email Verification Tool.
- Step 8: Scan open ports with our Port Scanner to assess server security posture.
- Step 9: Test redirects with our Redirect Checker to verify HTTP/HTTPS and www/non-www configurations.
- Step 10: Check if the server IP belongs to a cloud provider with our Cloud IP Check.
Best Practice: Run this complete audit whenever evaluating a domain for purchase, investigating suspicious websites, onboarding new business partners, or performing periodic security reviews of your own domain portfolio.
Frequently Asked Questions About WHOIS Lookup
What is a WHOIS lookup and what information does it show?
A WHOIS lookup online queries domain registries to reveal registration details including registrant name, registrar information, creation date, expiration date, nameservers, domain status codes, and abuse contact information. Due to GDPR, personal details are often redacted for privacy.
How to find the owner of a website with WHOIS privacy?
When WHOIS privacy masking is enabled, use the registrar abuse contact email or privacy proxy forwarding address shown in results. For legal matters, courts can compel registrars to reveal the actual owner behind WHOIS privacy shields.
How to check domain expiry date and registrar for free?
Enter any domain in our free WHOIS lookup online tool above. It queries the authoritative WHOIS server via Port 43 and returns the creation date, expiration date with days-remaining countdown, registrar name, and current domain status.
Can I do a WHOIS lookup for .ai and .io niche domains?
Yes. Our tool supports .ai, .io, .dev, .co, .app, .tech, .online, .xyz, and 20+ other TLDs. Each TLD routes to its correct authoritative WHOIS server for accurate results.
What does ClientTransferProhibited status mean?
ClientTransferProhibited is a registrar lock that prevents unauthorized domain transfers. It is a security feature protecting against hijacking. Other statuses include ClientHold (DNS suspended), PendingDelete (scheduled for release), and RedemptionPeriod (last recovery window).
How to track domain ownership history for free?
Our tool shows current registration data with domain age calculation. For historical ownership snapshots, services like DomainTools and the Wayback Machine provide archived WHOIS records showing past registrants, nameserver changes, and ownership transfers over time.
How to find the host of a website through WHOIS data?
Check the nameservers (NS) field. Nameservers containing "cloudflare" indicate Cloudflare, "awsdns" indicates AWS Route 53, "digitalocean" indicates DigitalOcean. Combine WHOIS with our DNS Lookup for complete hosting identification.
Is a domain available if WHOIS shows no results?
Likely yes. If WHOIS returns "No Match" or "Not Found," the domain is unregistered and probably available at standard prices. Our tool auto-detects availability. However, verify through a registrar before purchasing — some premium domains are reserved at higher prices.
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Unmask Any Domain's Registration Details
Free WHOIS Lookup — No Signup Required
Our WHOIS lookup online tool queries 25+ TLD registries to reveal domain ownership, registrar details, expiration dates, nameservers, status codes, and WHOIS privacy status. Check any domain instantly — .com, .io, .ai, .dev, and more.