What is RDAP? (and whatever happened to WHOIS)
Every website address is registered to someone. For forty years, the way to look up who — and when it expires, and where to report abuse — was a service called WHOIS. It's now being switched off and replaced by RDAP. Here's the plain-English version of what that means.
Every domain leaves a paper trail
When someone registers a domain like example.com, that registration gets recorded: when it was created, when it expires, which company it was bought through, and which servers it uses. This is registration data, and by design it's public — a bit like how a business license or a property deed is on the record.
A few different players keep these records:
- ICANN is the non-profit that sets the rules for domain names worldwide.
- A registry runs an entire ending — Verisign operates every .com, for instance — and holds the master list.
- A registrar is the company you actually buy a domain from, like Namecheap or GoDaddy. They're required to keep their customers' registration records available to the public.
Looking up that record is what this site does. The only question is how you ask for it — and that's where WHOIS and RDAP come in.
WHOIS: a directory from 1982
WHOIS is genuinely one of the internet's oldest surviving tools. Back when the network was ARPANET — a research project connecting a few dozen computers — a team at the Stanford Research Institute kept a directory of everyone on it. Want to know who was behind a given machine or handle? You could ask the directory: literally, who is this? Elizabeth Feinler and her group ran it, and in 1982 the lookup was written up as an official standard.
In those days the whole thing was small enough that the directory was a list of people — names, postal addresses, phone numbers. You connected to a single computer and typed a name. That informality is baked into WHOIS's DNA, and it's part of why it aged badly.
As the web exploded in the 1990s and domains went commercial, WHOIS was pressed into service as the domain-lookup tool, and it worked well enough for a long time. But a system designed for a friendly research network started to strain once it was answering for hundreds of millions of names.
Why WHOIS started to show its age
The problems piled up:
- No common format. Every registry answered in its own slightly different layout of plain text. Fine for a human squinting at it; a headache for any software trying to read it reliably.
- English, basically. It was never built for the world's scripts and languages, so names and addresses outside a narrow character set came out garbled.
- All or nothing on privacy. A record was fully public or it wasn't. When Europe's GDPR privacy law took effect in 2018, registrars had to react bluntly — blanking out personal details behind "Redacted for Privacy." Useful data for legitimate purposes vanished along with the personal data.
- No structure, no security. Answers came over a plain, unencrypted connection with no standard way to handle errors or verify anything.
RDAP: the modern replacement
RDAP — the Registration Data Access Protocol — was built by the internet's standards body to fix exactly those problems, while answering the same questions. It's not a reinvention of what registration data is; it's a much better way of asking for and delivering it.
- Structured, consistent answers. Every RDAP server replies in the same predictable, machine-readable format, so tools (like this one) can present it cleanly and consistently.
- Works in every language. Internationalized names and addresses are handled properly.
- Modern and secure. It runs over the same encrypted web technology as any normal website.
- Room for tiered access. Instead of one blunt public/hidden switch, RDAP is designed so that, in time, verified parties could see more than an anonymous visitor — without exposing everyone's details to everyone.
The short version: WHOIS and RDAP answer the same question — "who registered this, and what are the details?" RDAP just does it in a clean, standardized, modern way instead of forty-year-old plain text.
WHOIS is being switched off
This isn't a prediction — it's happening. ICANN set a deadline of January 2025, after which the companies that run .com, .org, .net and the other generic endings are no longer required to offer the old WHOIS service at all. RDAP is now the official standard for them.
(Country-code endings like .uk or .de set their own timelines, so a few still run the older system for now — which is why a lookup here occasionally can't find an RDAP server for one of them.)
Where rdap.com fits in
This site is a friendly front door to RDAP. You type a domain, IP address, or network number, and your browser asks the official RDAP servers directly and shows you the answer in plain language — no account, no middleman server storing your searches. If you've ever used a WHOIS lookup before, this is the same idea, built on the system that's replacing it.
Want the deeply technical version? The RDAP specifications live in the IETF's RFCs (9082, 9083, and 9224 among them), and about.rdap.org collects implementer resources. ICANN's site covers the policy side of the WHOIS-to-RDAP transition.