RDAP Lookup: the next-generation registration data protocol

RDAP lookup key facts

• RDAP (Registration Data Access Protocol) is the successor to WHOIS, defined by RFC 7480–7484 (2015), served over HTTPS with structured JSON.
• ICANN's port-43 WHOIS contractual obligation for gTLDs was formally sunset on January 28, 2025 — RDAP is now the only mandatory protocol for gTLD registration data.
• TWNIC has RDAP live for .tw/.台灣 (ccrdap.twnic.tw), registered in the IANA bootstrap; legacy WHOIS still runs in parallel with no announced shutdown date.
• This site queries RDAP first for every lookup: it resolves each TLD's RDAP server from the IANA bootstrap (RFC 9224) and only falls back to port-43 WHOIS when a TLD has no RDAP.
• Every result is labeled with its data source (RDAP or WHOIS), so you can verify which protocol served your lookup.

RDAP support at a glance

What is RDAP?

RDAP (Registration Data Access Protocol) was published by the IETF in 2015 as RFC 7480–7484 as the successor to legacy WHOIS, moving registration data lookups onto the modern HTTP stack:

• Served over HTTPS (TLS-encrypted), replacing cleartext TCP port 43.
• Responses are standardized JSON (application/rdap+json) with consistent fields across TLDs — directly machine-parseable.
• Contacts are structured as jCard (RFC 7095) instead of free-form text that every registry lays out differently.
• Standard HTTP status codes: 404 means the domain is not registered, 429 means you are rate-limited — failure causes are explicit.

The query and response formats were updated by RFC 9082 and RFC 9083 (2021); server discovery is specified by RFC 9224 (2022). For a field-by-field comparison of the two protocols, see this site's full WHOIS vs RDAP article.

How this site runs RDAP lookups

Every domain lookup on whois.net.tw is RDAP-first and follows the standards end to end:

• It resolves the TLD's official RDAP server from the <ianaBootstrap>IANA bootstrap registry</ianaBootstrap> (RFC 9224) — no hard-coded addresses.
• It queries the registry's RDAP server, then automatically follows the registrar link in the response for registrar-level detail.
• Only when a TLD has no RDAP or the query fails does it fall back to legacy port-43 WHOIS.
• The result page labels the data source as RDAP or WHOIS, so every lookup is verifiable.

That includes .tw: TWNIC's RDAP server accepts HTTP/2 connections only, and this site's backend connects over HTTP/2 directly to the official endpoint — .tw results are genuine RDAP structured data.

RDAP status for .tw (TWNIC)

TWNIC, the registry for .tw and .台灣, has RDAP formally in service and is in a dual-track transition:

• RDAP endpoints are live: https://ccrdap.twnic.tw/tw/ for .tw and https://ccrdap.twnic.tw/taiwan/ for .台灣, both registered in the IANA bootstrap.
• Legacy port-43 WHOIS (whois.twnic.net.tw) still runs in parallel.
• TWNIC has not announced a shutdown date for legacy WHOIS, but the direction matches the global trend: RDAP progressively replaces WHOIS.
• Lookups for .tw domains on this site already go through RDAP — nothing to change on your side.

See TWNIC's official site for its RDAP service documentation; this page will track the .tw transition timeline as it develops.

How to call the RDAP API directly

RDAP is an open HTTP API — developers can call it directly, no API key required:

• The domain query format is the RDAP base URL + /domain/ + domain name, e.g. https://rdap.verisign.com/com/v1/domain/example.com or https://ccrdap.twnic.tw/tw/domain/twnic.tw.
• Each TLD's RDAP base URL is listed in the IANA bootstrap file (https://data.iana.org/rdap/dns.json).
• Send an <code>Accept: application/rdap+json</code> header with your requests.
• A 404 response means the domain is not registered; 429 means you exceeded the registry's rate limit — retry later.

Note: some registries' RDAP servers (TWNIC, for example) accept HTTP/2 only — HTTP/1.1 clients get 426 Upgrade Required. Use curl or any HTTP/2-capable client and the data comes back fine.

WHOIS sunset progress: done for gTLDs, in transition for ccTLDs

"WHOIS is being retired" is not future tense — it is already happening, at different speeds per scope:

• gTLDs (.com/.net/.org, etc.): ICANN's port-43 WHOIS contractual obligation for registries and registrars was formally sunset on January 28, 2025 — RDAP is the only mandatory protocol.
• ccTLDs (.tw/.jp/.uk, etc.): not bound by ICANN contracts; each national registry sets its own timeline, and most major ccTLDs already serve RDAP.
• .tw: TWNIC's RDAP is live, legacy WHOIS runs in parallel, and no shutdown date has been announced.

Practical advice: make RDAP the primary interface for any new system (RDAP-first) and keep WHOIS only as a fallback for the few TLDs without RDAP — exactly what this site does. See the ICANN RDAP page.

How to run an RDAP lookup

1. 1

   Enter a domain name

   Type any domain (e.g. example.com or twnic.tw) into the homepage search box — this site automatically queries RDAP first.

2. 2

   Check the data-source label

   The result page's Data Source field shows whether the lookup came back via RDAP or WHOIS; TLDs with RDAP support (including .tw and all gTLDs) show RDAP.

3. 3

   Inspect the raw JSON response

   Expand the raw-data block to see the complete RDAP JSON response (events, entities, nameservers and other standard fields) — directly comparable against the RFC 9083 field definitions.

Try an RDAP lookup now

Enter any domain — this site fetches structured registration data via RDAP and clearly labels the data source.

References

• RFC 7480 — RDAP over HTTP — RDAP transport layer
• RFC 9082 — RDAP Query Format — RDAP query format
• RFC 9083 — RDAP JSON Responses — RDAP JSON response format
• RFC 9224 — Finding the Authoritative RDAP Service — RDAP server discovery (bootstrap)
• IANA — RDAP Bootstrap Service Registry — RDAP endpoints for each TLD
• ICANN — Registration Data / RDAP — gTLD RDAP policy and status
• TWNIC — How To Use the RDAP Service — Official RDAP endpoints for .tw/.台灣