RDAP Server List

What is an RDAP server?

An RDAP server is an HTTPS web service, run by a domain registry, that answers questions about the domain names it manages. Ask it about a domain and it returns the registration record as JSON: the registrar, key dates, status codes, name servers, DNSSEC details and, where the registry publishes them, contact details. RDAP (Registration Data Access Protocol) is the successor to WHOIS: read what RDAP is for a full introduction, or RDAP vs WHOIS for how the two compare.

The protocol is a set of IETF standards: RFC 7480 (HTTP usage), RFC 7481 (security), RFC 9082 (query format), RFC 9083 (JSON responses) and RFC 9224 (finding the right server). Responses use the application/rdap+json media type.

How clients find an RDAP server: the IANA bootstrap

There is no single central RDAP server. Instead, IANA publishes bootstrap registry files, defined in RFC 9224, that map each part of the namespace to the base URL of the server responsible for it. For domain names that file is dns.json, which lists the RDAP server of every top-level domain whose registry has one. (IANA publishes separate bootstrap files for IP address blocks and AS numbers, whose registration data the five regional internet registries serve over RDAP.)

To look up example.com, a client takes the TLD (com), finds its entry in https://data.iana.org/rdap/dns.json, appends the query path to the base URL and sends an HTTPS GET request. A TLD only appears in the bootstrap file once its registry has registered an RDAP service with IANA. Generic TLD registries must run RDAP under their ICANN agreements; country-code registries decide for themselves.

RDAP query paths

RFC 9082 defines the paths a client appends to a server's base URL. These are the ones a domain registry answers:

RFC 9082 defines a few other paths as well, plus optional searches such as domains?name=, which many servers do not offer.

How W.is uses this list

W.is keeps its own copy of the domain mapping, built from the IANA root zone database and bootstrap registry plus a few ccTLD RDAP servers that work but are not yet listed in the bootstrap file. Every endpoint below is written in the form <base>/domain/, so the lookup URL is simply the endpoint followed by the domain name, with internationalized names in their punycode (A-label) form.

For example, the RDAP record of google.com comes from:

curl -H 'Accept: application/rdap+json' https://rdap.verisign.com/com/v1/domain/google.com

Or let W.is run the query and format the answer: google.com RDAP lookup.