rdap-java

A lightweight, high-performance RDAP client library for Java. A modern, structured alternative to legacy WHOIS socket queries to check domain registration status and availability.

Supports all TLDs via IANA bootstrap data, automatic RDAP server discovery, and built-in fallbacks.

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Features

• Domain Availability Check: Instantly determine if a domain is registered or available.
• Universal TLD Support: Covers ~1200+ TLDs via dynamic IANA bootstrap + curated fallbacks for unlisted registries.
• Automatic Server Discovery: Resolves official RDAP base URLs per TLD automatically with thread-safe caching.
• Server Failover: Built-in fallback mechanism across multiple RDAP servers per TLD.
• IDN & Punycode Ready: Native handling for internationalized domain names (e.g., umlauts, non-Latin scripts).
• Nameserver Extraction: Easily extract authoritative nameservers from RDAP responses.
• Custom Endpoints: Register custom RDAP server endpoints at runtime.
• Zero Heavyweight Frameworks: Uses pure Java 11+ HttpClient and org.json (~5 KB library overhead).

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Requirements

• Java 11 or higher

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Installation

Gradle (Kotlin DSL)

repositories {
    mavenCentral()
}

dependencies {
    implementation("com.slxca:rdap-java:1.0.0")
}

Gradle (Groovy DSL)

repositories {
    mavenCentral()
}

dependencies {
    implementation 'com.slxca:rdap-java:1.0.0'
}

Maven

<dependency>
    <groupId>com.slxca</groupId>
    <artifactId>rdap-java</artifactId>
    <version>1.0.0</version>
</dependency>

Manual Download

Grab the latest pre-built .jar from the Releases page.

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Usage

Check Domain Availability

import com.slxca.rdap.RDAPClient;
import com.slxca.rdap.RDAPResult;
import com.slxca.rdap.RDAPException;

public class Main {
    public static void main(String[] args) {
        RDAPClient client = new RDAPClient();

        try {
            RDAPResult result = client.checkDomain("example.com");

            if (result.isRegistered()) {
                System.out.println(result.getDomain() + " is already taken.");
                System.out.println("RDAP Server: " + result.getServerUrl());
            } else {
                System.out.println(result.getDomain() + " is available for registration!");
            }
        } catch (RDAPException e) {
            System.err.println("RDAP lookup failed: " + e.getMessage());
        }
    }
}

Extract Nameservers

RDAPResult result = client.checkDomain("google.com");

if (result.isRegistered()) {
    System.out.println("Nameservers:");
    for (String ns : result.getNameservers()) {
        System.out.println(" - " + ns);
    }
}

Custom RDAP Server Registration

If a registry is not part of the IANA bootstrap registry or uses a dedicated endpoint, register it manually:

client.registerServer("io", "[https://rdap.afilias.net/rdap/](https://rdap.afilias.net/rdap/)");
RDAPResult result = client.checkDomain("example.io");

Custom HttpClient Configuration

Pass your own configured HttpClient (e.g., custom timeouts, proxy settings):

import java.net.http.HttpClient;
import java.time.Duration;

HttpClient customHttp = HttpClient.newBuilder()
    .connectTimeout(Duration.ofSeconds(5))
    .build();

RDAPClient client = new RDAPClient(customHttp);

Command Line Interface (CLI)

Run the packaged JAR directly from your terminal:

java -jar rdap-java.jar google.com

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API Reference

RDAPClient

RDAPResult

Exceptions

• RDAPException – Thrown on network issues, HTTP errors other than 404, or if no RDAP endpoint was discoverable.
• IllegalArgumentException – Thrown when passing null, empty, or malformed domain strings.

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How It Works

1. TLD Extraction: Normalizes the input and isolates the top-level domain (e.g., sub.example.co.uk or münchen.de via IDN Punycode).
2. Endpoint Resolution: Checks custom registered servers first, then queries cached IANA bootstrap data, and falls back to curated registry lists.
3. HTTP Query: Sends an authenticated HTTP GET request with header Accept: application/rdap+json.
4. Status Evaluation: Treats HTTP 200 as registered and parses details; treats HTTP 404 as available.

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Supported TLDs

Missing a TLD? Feel free to open an issue or submit a Pull Request.

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License

This project is licensed under the MIT License