RegistryFusion™ unified Whois API

One access point. One data format. A world of possibilities.

RegistryFusion unified Whois provides a single, consistent, programmable interface to the Whois system. It takes your domain or IP address query, automatically finds the correct server, and returns consistent machine-readable results.

Whois API XML outputThis unified interface enables a wide variety of advanced applications:

  • Investigating spam, fraud, intrusions, and other online misbehavior
  • Tracking domain registrations
  • Checking domain name availability
  • Advanced Whois web pages
  • Detecting (credit card) fraud
  • Researching Internet infrastructure and usage
  • Locating users geographically

The RegistryFusion system is available as a service hosted on our server and also as software that you can install on your own machines. All solutions share the following features:


  • Automatically determines the correct domain to get records for when given an arbitrary domain name. For example, when given www.yahoo.com it determines that the name to send in the query to the whois server is yahoo.com. A trickier example: given athletic.shoe.shopping.seoul.kr, the correct query domain is shopping.seoul.kr.
  • Automatically finds and queries the correct Whois server for IP addresses, gTLD domains, and ccTLD domains
  • Works with both thick and thin Whois registries—follows referral chains, doing multiple queries as needed to get the most specific results
  • Normalizes end-of-line characters in server responses (changes all single CRs and LFs to CRLF pairs)
  • Normalizes the character sets of Whois records to Unicode
  • Separates header and footer text (terms of service, advertisements) from record text
  • Parses record text into consistent, well-defined fields
  • Returns an indication of whether a domain is available (i.e., whether the query found a matching record)
  • Is regularly tested and updated for accuracy
  • Includes parsing support for the 5 major regional registries (ARIN, RIPE, APNIC, LACNIC, AFRINIC).
  • Includes parsing support for over 90% of .com, .net, and .org domains. See the coverage details.

Hosted Web service

The Whois service hosted at Hexillion provides a simple, cross-platform way of getting Whois records in a consistent XML or JSON format. It consists of a REST-style web service accessible via HTTP.

Special features of the hosted web service:

  • Keeps Whois server lists and parsing code up-to-date for you—you don't have to do anything
  • Uses caching and a large pool of diverse IP addresses to avoid the query limits you would encounter when doing Whois queries from a single IP address
  • Works over basic HTTP, thus avoiding firewall-related problems of accessing Whois servers on port 43
  • Works with any platform or language that can make HTTP requests and parse XML or JSON
  • Requires very little up-front investment because it is billed according to usage
The service uses the accounts and pricing on our CentralOps.net site. Thus, as a bonus, your account for the Whois service also gives you extended access to our CentralOps.net utilities.

Online demo
Enter a domain name or IP address
output format:  

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Installable software

The RegistryFusion system currently offers a choice of three interfaces that you can install on your own Windows machines. Because they operate from your IP addresses, queries you make with these tools will be subject to the usual query limits imposed by Whois server operators.

HexWhois™ .NET Class Library

The class library offers maximum control of queries and returned data. You can use it from both .NET applications and COM clients.

Special features of the class library:

  • Provides a "raw" query method for doing your own non-automatic queries
  • Can parse raw Whois records obtained through past queries with other tools—old records you have stored in a database, for example
  • Puts Whois data into program-friendly .NET collections and can transform XML results from any of the other RegistryFusion interfaces into those collections
  • Includes classes (in the HexNetwork library) for working with IP addresses and Internationalized Domain Names

download | requirements | pricing and editions | order online

Whois XML Web Service

The XML Web Service is an ASP.NET application that takes query input from an HTTP GET or POST and returns results as XML.

Special features of the installable web service:

  • Provides a means of limiting quantity and rate of usage by IP address on a local network
  • Can cache XML results in a SQL Server database to avoid the cost of duplicate queries

Note: Requires IIS. If using IIS 7 (Windows Vista, Windows Server 2008), you will need to turn on IIS 6 metabase compatibility (IIS 6 management console is not necessary).

Online demo
Enter a domain name or IP address

download | requirements | pricing and editions | order online

Whois XML Proxy Server

The XML Proxy Server runs as a Windows Service (no IIS needed) and listens on port 43, just as a regular Whois server does. It takes a simple string of input and returns the same XML as the web service.

Special features of the installable proxy server:

  • Provides a means of limiting quantity and rate of usage by IP address on a local network
  • Can cache XML results in a SQL Server database to avoid the cost of duplicate queries

download | requirements | pricing and editions | order online


  • Windows 2000 SP4, XP SP2, Server 2003, Vista, Server 2008 or later (32-bit or 64-bit). The HexWhois .NET class library will also work on Windows 98 and ME.
  • The web service requires Internet Information Server (IIS).
  • Microsoft .NET Framework 2.0 SP1, 3.0 SP1, 3.5 SP1, or later. (To see if you already have it, look for "Microsoft .NET Framework" under Control Panel -> Add/Remove Programs.) You can download it from Microsoft or get it through Windows Update.

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