The Registration Data Access Protocol (RDAP) is the successor to WHOIS. Like WHOIS, RDAP provides access to information about Internet resources (domain names, autonomous system numbers, and IP addresses). Unlike WHOIS, RDAP provides:

• A machine-readable representation of registration data;
• Differentiated access;
• Structured request and response semantics;
• Internationalisation;
• Extensibility.

RDAP.org aims to support users and developers of RDAP clients by providing a "bootstrap server", i.e. single end point for RDAP queries. RDAP.org aggregates information about all known RDAP servers. RDAP clients can send RDAP queries to RDAP.org, which will then redirect requests to the appropriate RDAP service.

How To Use RDAP.org

Client Implementers

If you are developing an RDAP client, configure it to send HTTP requests to https://rdap.org/<type>/<object>, where <type> is the object type (one of domain, ip, autnum, entity etc) and <object> is the object identifier (eg example.com, 192.168.0.1, 64496, etc).

HTTP Status Codes

• 302 – occurs when RDAP.org knows of an RDAP service which is authoritative for the requested resource. Follow the URL listed in the Location header.
• 400 – occurs when RDAP.org receives an invalid request (malformed path, unsupported object type, invalid IP address, etc).
• 403 – occurs if you've been blocked due to abuse or other misbehaviour.
• 404 – occurs when RDAP.org doesn’t know of an RDAP service which is authoritative for the requested resource. RDAP.org only knows about RDAP servers that are registered with IANA.
• 500 – occurs when RDAP.org is broken in some way.

Note that these status codes only apply to the RDAP.org service itself, not the registry RDAP services themselves.

IANA RDAP Service

IANA has recently launched an RDAP service. Each TLD has its own RDAP record at https://rdap.iana.org/domain/{TLD} (root.rdap.org/domain now redirects to this server). You can also get an RDAP search result listing all TLDs using https://root.rdap.org/domains.

Additional Resources

Apart from the DNS, ASN and IP registries which are listed in the IANA registry, and IANA's own RDAP server, RDAP.ORG also provides an RDAP service for ICANN-accredited registrars. You can obtain RDAP records for ICANN-accredited registrars at https://registrars.rdap.org/entity/{NNNN}-iana where {NNNN} is the numeric IANA ID. These records are synthesised from data published by IANA and ICANN.

References

These are the authoritative references for the RDAP protocol specifications:

• RFC 7480: HTTP Usage in the Registration Data Access Protocol (RDAP)
• RFC 7481: Security Services for the Registration Data Access Protocol (RDAP)
• RFC 9083: JSON Responses for the Registration Data Access Protocol (RDAP)
• RFC 9224: Finding the Authoritative Registration Data (RDAP) Service
• RFC 8056: Registration Data Access Protocol (RDAP) Object Tagging
• RFC 8977: Registration Data Access Protocol (RDAP) Query Parameters for Result Sorting and Paging
• RFC 8982: Registration Data Access Protocol (RDAP) Partial Response
• RFC 9082: Registration Data Access Protocol (RDAP) Query Format
• RFC 9536: Registration Data Access Protocol (RDAP) Reverse Search
• RFC 9537: Redacted Fields in the Registration Data Access Protocol (RDAP) Response
• All generic TLDs (and some ccTLDs) are compliant with the gTLD RDAP Profile.
• The Number Resource Organization (NRO) developed the NRO RDAP profile for RIR RDAP services.

Many RDAP servers have also implemented their own custom extensions, some of which may be found in the RDAP Extensions registry at IANA.

The RDAP Book

Andy Newton, one of the creators of RDAP, has published A Guide to the Registration Data Access Protocol (RDAP), which is a definitive guide to implementing, using, and understanding all aspects of RDAP.

Privacy Considerations

If you use RDAP.org to perform RDAP queries, your queries will be logged, alongside your IP address. These logs are not disclosed to anyone and are deleted within a few days. RDAP.org will not set any cookies in your browser.

Feedback

If you would like to submit feedback, please email feedback@rdap.org.

Supporting RDAP.ORG

If your organisation depends on RDAP.org, then please consider supporting it, since it's not free to operate and requires ongoing maintenance and management.

About RDAP.org

You can review the code which RDAP.org uses on GitHub.

RDAP.org is maintained by me, Gavin Brown. While I am currently an employee of ICANN, I run this service in my own time and at my own cost.