Why WHOIS is Deprecating and How to Use RDAP in Java

The Problem with WHOIS

For decades, the WHOIS protocol was the go-to solution to check domain ownership, IP address allocations, and Autonomous System Numbers (ASNs). However, WHOIS has a massive flaw: it lacks a standardized format. Parsing plain text responses from hundreds of different registries is an absolute nightmare.

Enter RDAP (Registration Data Access Protocol). It’s the official, modern successor to WHOIS. It runs over HTTP and delivers responses in structured JSON.

Introducing rdap-java

While working on infrastructure and DNS monitoring utilities, I realized that existing Java solutions for RDAP were either part of massive, bloated frameworks or heavily outdated.

To solve this, I built rdap-java—a lightweight, dependency-minimal client specifically designed to fetch and map RDAP data cleanly.

Quick Code Example

Here is how simple it is to look up a domain using the package:

// Quick draft example of querying a domain

RdapClient client = new RdapClient();

DomainResponse response = client.queryDomain("github.com");



System.out.println("Registrar: " + response.getRegistrarName());

System.out.println("Status: " + response.getStatus());

(Note: Feel free to adjust this snippet to match your exact API syntax!)

Open Source & Feedback

The project is fully open-source under the MIT license. If you are building anything in the networking, DevOps, or cybersecurity space with Java, I’d love for you to try it out.

Check out the repository here: https://github.com/slxca/rdap-java

What features should I add next? Let me know in the comments!