RDAP, not port-43 WHOIS
Classic WHOIS is a plain-text protocol on TCP port 43 with no standard layout, so every registry formats its answers differently. This tool uses its successor, RDAP (Registration Data Access Protocol), which returns JSON over HTTPS and is defined in RFC 7480 to RFC 7484 (the newer RFC 9082 and 9083 update the query and response formats). The server asks rdap.org, a bootstrap service that redirects each query to the RDAP server of the registry responsible for that top-level domain, and then reads these fields:
| Shown | RDAP source |
|---|---|
| Registrar | The entity with the registrar role, using its vCard "fn" name, or its handle if no name is given |
| Created | Event registration |
| Last updated | Event last changed |
| Expires | Event expiration |
| Nameservers | The ldhName of each listed nameserver |
| DNSSEC | Enabled only if secureDNS.delegationSigned is true |
The expiry countdown
The page converts the expiry date to a day count: expiry time minus the current time, divided by 86,400,000 milliseconds per day and rounded. For a domain with an expiry of 15 March 2027, checked on 6 October 2026, the difference is 160 days, shown as "expires in 160 days". Under 30 days the label turns red, and after the date it reads "expired N days ago". Dates are displayed in your own locale format, and "Unknown" appears if the registry omitted one.
Reading status codes
Each code returned is listed with a short explanation. These are EPP statuses, and the ones you will see most often are:
clientTransferProhibited: a registrar lock. It is a good default and is removed deliberately when you transfer away.serverTransferProhibited,serverDeleteProhibited,serverUpdateProhibited: locks applied by the registry itself, common on high-value domains.clientHoldorserverHold: the domain is removed from DNS and will not resolve, often due to unpaid renewal or a dispute.autoRenewPeriod,redemptionPeriod,pendingDelete: the lifecycle after expiry, ending in release. Redemption usually involves an extra fee, and exact lengths vary by registry.
A code outside the built-in legend gets a generic note instead of an explanation.
What you will not get
- Owner details. The tool does not display registrant names, emails or phone numbers. Many registries redact them anyway, particularly for domains owned by individuals and for registrations covered by GDPR.
- Coverage gaps. A TLD without a public RDAP service, or a domain that is not registered, returns an error ("Domain not found in RDAP" for a 404).
- IP addresses. A bare IPv4 or IPv6 address is not a domain, and RDAP IP lookups are a different query, so the tool stops with a clear message instead of sending it.
- Single-label names. The domain must contain at least one dot. Paste a full URL if you like; it is reduced to the hostname, and international names are converted to their
xn--form. - Subdomains. Registration data belongs to the registered domain, so querying
blog.example.comis not expected to return a record of its own. Enterexample.com.
Pair this with the DNS lookup to compare the nameservers registered here with the NS records actually being served. A mismatch often explains a site that did not move after a DNS change.