What is RDAP and how is it different from WHOIS?

RDAP (Registration Data Access Protocol) is the IETF standard that replaces the legacy WHOIS protocol. Where WHOIS returns unstructured free text over the unencrypted port 43 — formatted differently by every registry — RDAP returns structured JSON over HTTPS, supports internationalized data, and is mandated by ICANN for gTLD registries and operated by all five Regional Internet Registries. This API queries RDAP for you and flattens the complex, nested response into clean, stable JSON.

Which endpoints does the RDAP API provide?

There are two GET endpoints. /rdap/v1/domain takes a domain query parameter and returns a flattened domain registration record (status, nameservers, registrar, dates, DNSSEC). /rdap/v1/ip takes an ip parameter — an IPv4 address, IPv6 address, or CIDR block — and returns a flattened network record with handle, name, type, country, CIDR, address range, and abuse contact. There is also a health check endpoint.

Can I use this API to check if a domain is available?

Yes, as a heuristic. When the authoritative registry reports a domain as not found, the API returns a 200 with available:true and empty fields, which indicates the name is likely unregistered (registered domains carry available:false). If the TLD has no RDAP service at all, the API returns a 404 with available:null so you can tell 'likely free' apart from 'unknown'. This is a strong signal for availability tools, but it is not a guarantee of registrability — always verify with a registrar before purchase.

Why are registrant contact details often empty?

Due to GDPR and similar privacy regulations, most gTLD registries redact personal registrant contact details (name, email, phone) at the source. This is a property of RDAP itself, not the API. You can still rely on non-personal fields — domain status flags, nameservers, registrar and IANA ID, and registration/expiration/last-changed dates — which remain fully populated. For IP lookups, organization and abuse-contact data is typically available.

How fast is the API and where does the data come from?

The API runs on a global edge network and typically responds in under a second. Each query is routed through rdap.org, the IANA bootstrap redirector, which points to the authoritative registry (for domains) or Regional Internet Registry (for IPs). We follow that redirect and fetch the record straight from the source, so the data is authoritative rather than scraped or reconstructed from legacy WHOIS text.

What happens when an upstream RDAP server has a problem?

Upstream conditions are mapped to clear HTTP status codes. A 400 means the supplied domain or IP was invalid. A likely-unregistered domain is not an error: it is a 200 with available:true. A 404 means the TLD has no RDAP service or no registry holds a record for the IP. A 502 means the upstream returned an invalid or failed response, a 503 means the registry rate-limited our queries, and a 504 means the upstream request timed out; these failed lookups are not billed. A 429 is your own plan's rate limit or quota. Successful lookups are cached for up to an hour (add nocache=1 for a fresh one). This lets your client implement precise retry and backoff logic.

Does the IP endpoint support IPv6 and CIDR blocks?

Yes. The ip parameter accepts an IPv4 address (e.g. 8.8.8.8), an IPv6 address, or a CIDR block (e.g. 8.8.8.0/24). The response includes the ip_version field along with the network's CIDR, start and end addresses, parent handle, registrant, and abuse contact — ideal for ASN enrichment, fraud scoring, and security tooling.

Modern WHOIS for domains and IPs, in clean JSON

RDAP API

The RDAP API gives you authoritative domain and IP registration data through RDAP (Registration Data Access Protocol), the IETF standard that replaces the old, unstructured, rate-limited WHOIS protocol. Every request is routed through the IANA bootstrap registry to the authoritative registry or Regional Internet Registry, so you always get data straight from the source.

RDAP responses are deeply nested, jCard/vCard-encoded, and inconsistent across registries. This API does that work for you, flattening everything into a clean, stable JSON object with domain status flags, nameservers, registrar, registration dates, DNSSEC details, and full IP network records — no scraping, no flaky port-43 WHOIS servers, no brittle text parsing.

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Key features

Domain lookups with status, nameservers, registrar, and dates
IPv4, IPv6, and CIDR network lookups with abuse contacts
Routed through the IANA RDAP bootstrap to authoritative registries
Flattened, stable JSON instead of nested jCard/vCard
Full DNSSEC details including DS records
Available-domain heuristic (a 200 with available:true when the registry has no record)
Graceful handling of upstream rate limits, timeouts, and TLDs without RDAP

Built for

Domain availability and registration checks
Brand and trademark monitoring
Fraud scoring and risk assessment
IP and ASN enrichment for security tooling
Abuse contact discovery for takedown workflows
Domain expiration and renewal monitoring
Threat intelligence and OSINT investigations
Compliance and registrar auditing

MCP · for your agent

Hand the RDAP API to your agent

Connect Claude, Cursor or any MCP client once, then ask in plain words. Your agent finds this API, reads its docs and makes the call: 5 credits per call, the same as REST, from your team's balance.

Connect your agent

Check if a domain is taken

“Is northwind-analytics.com available? If not, who's the registrar and when does it expire?”

list_apis · get_api_docsfree

api_request GET /rdap/v1/domain?domain=northwind-analytics.com 5 cr

Available, or the registrar, status and creation and expiry dates if it's registered.

Watch domain renewals

“List expiry dates for our 6 domains, including the .io and .co.uk ones, and warn me about any expiring within 90 days.”

list_apis · get_api_docsfree

api_request GET /rdap/v1/domain?domain=example.net 5 cr

+ Whois Lookup API5 cr

Registrar and expiry per domain, soonest first, with WHOIS filling gaps where RDAP has none.

Report abuse from an IP

“A single IP, 198.51.100.23, is hammering our login page. Who owns that network and where do I send an abuse report?”

list_apis · get_api_docsfree

api_request GET /rdap/v1/ip?ip=198.51.100.23 5 cr

+ IP Intelligence API5 cr

Network name, range, country and abuse contact, plus the ASN, ready for the report.

$ claude mcp add --transport http apicodex https://mcp.apicodex.io

Illustrative asks; the calls and prices are real. Claude, Cursor, VS Code and Windsurf setup: mcp.apicodex.io

Try it

Build the request for your data

Edit the parameters below and see the exact request and curl command you'd send. No key required to preview.

GET /rdap/v1/domain

Open in Playground

Parameters

domain

apikey

Request · HTTP

GET /rdap/v1/domain?domain=example.com&apikey=YOUR_API_KEY HTTP/1.1
Host: api.apicodex.io

Response · JSON 200 OK

{
"domain": "example.com",
"handle": "2336799_DOMAIN_COM-VRSN",
"status": [
  "client delete prohibited",
  "client transfer prohibited",
  "client update prohibited"
],
"nameservers": [
  { "name": "a.iana-servers.net" },
  { "name": "b.iana-servers.net" }
],
"registrar": {
  "name": "RESERVED-Internet Assigned Numbers Authority",
  "iana_id": "376",
  "url": "http://res-dom.iana.org"
},
"registration_date": "1995-08-14T04:00:00Z",
"expiration_date": "2025-08-13T04:00:00Z",
"dnssec": true,
"source": "rdap.org"
}

Run it with your key

Documentation

RDAP API Documentation

The RDAP API exposes two simple GET endpoints — one for domains and one for IPs/CIDR blocks. Queries are routed through rdap.org (the IANA bootstrap redirector) to the authoritative registry or RIR, then flattened into clean, stable JSON. Note that, due to GDPR, most gTLD registrant contact details are redacted at the source; status, nameservers, registrar, and dates remain reliable.

Base URL

url

https://api.apicodex.io/rdap

Authentication

Authenticate by passing your API key as a query parameter, or by sending it in an X-Api-Key header:

headers

GET /rdap/v1/domain?domain=example.com&apikey=YOUR_API_KEY

Request and response

Illustrative values. Confirm current endpoint behavior, quotas, and data freshness in the API documentation before production use.

request · http

GET /rdap/v1/domain?domain=example.com&apikey=YOUR_API_KEY HTTP/1.1
Host: api.apicodex.io

response · json

{
"domain": "example.com",
"handle": "2336799_DOMAIN_COM-VRSN",
"status": [
  "client delete prohibited",
  "client transfer prohibited",
  "client update prohibited"
],
"nameservers": [
  { "name": "a.iana-servers.net" },
  { "name": "b.iana-servers.net" }
],
"registrar": {
  "name": "RESERVED-Internet Assigned Numbers Authority",
  "iana_id": "376",
  "url": "http://res-dom.iana.org"
},
"registration_date": "1995-08-14T04:00:00Z",
"expiration_date": "2025-08-13T04:00:00Z",
"dnssec": true,
"source": "rdap.org"
}

Code examples

cURL

curl --request GET \
  --url 'https://api.apicodex.io/rdap/v1/domain?domain=example.com' \
  --header 'X-Api-Key: YOUR_API_KEY'

JavaScript/Node.js

const url = 'https://api.apicodex.io/rdap/v1/domain?domain=example.com';

const options = {
  method: 'GET',
  headers: {
    'X-Api-Key': 'YOUR_API_KEY'
  }
};

try {
  const response = await fetch(url, options);
  const data = await response.json();
  console.log(data);
} catch (error) {
  console.error(error);
}

Python

import requests

url = "https://api.apicodex.io/rdap/v1/ip"

querystring = {"ip": "8.8.8.8"}

headers = {
    "X-Api-Key": "YOUR_API_KEY"
}

response = requests.get(url, headers=headers, params=querystring)

print(response.json())

Endpoints

GET /v1/domain

RDAP/WHOIS lookup for a domain. Returns a flattened domain record with status, nameservers, registrar, dates, and DNSSEC. When the registry reports the domain as not found, it still returns a 200: the same record shape with available:true and empty fields. Subdomains are reduced to the registrable domain.

/v1/domain?domain=example.com&apikey=YOUR_API_KEY

GET /v1/ip

RDAP lookup for an IPv4/IPv6 address or CIDR block. Returns a flattened network record with handle, name, type, country, CIDR, address range, and abuse contact.

/v1/ip?ip=8.8.8.8&apikey=YOUR_API_KEY

Domain Endpoint Parameters

Required parameters

domain Domain name to query. Accepts a bare domain, an FQDN with trailing dot, a Unicode (IDN) name (converted to punycode), punycode (xn--) labels and TLDs, or a pasted URL (the hostname is extracted). Normalized to lowercase and reduced to the registrable domain (www.bbc.co.uk is looked up as bbc.co.uk); a bare public suffix such as co.uk is a 400.
apikey Your API key. Pass it as a query parameter, or send it in an X-Api-Key header instead.

IP Endpoint Parameters

Required parameters

ip An IPv4 address, IPv6 address, or CIDR block to look up, e.g. 8.8.8.8 or 8.8.8.0/24.
apikey Your API key. Pass it as a query parameter, or send it in an X-Api-Key header instead.

Pricing

RDAP API Pricing

This API costs 5 credits per request. Credits are shared across every API on your plan.

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FAQ

RDAP API

Key features

Built for

Hand the RDAP API to your agent

Check if a domain is taken

Watch domain renewals

Report abuse from an IP

Build the request for your data

RDAP API Documentation

Base URL

Authentication

Request and response

Code examples

Endpoints

GET /v1/domain

GET /v1/ip

Domain Endpoint Parameters

Required parameters

IP Endpoint Parameters

Required parameters

RDAP API Pricing

Free

Starter

Pro

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Frequently asked questions

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