Reverse WHOIS API calls domains with a registrant detail | WhoisXML API

Find all domain names which contain a specified search terms in their WHOIS records

With one API call for search terms such as a domain owner’s name, email address, phone number, postal address, etc., you will get a list of all the linked domains that contain the identifier.

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500 free API credits. No credit card required.

13.7+ billion Historic WHOIS Records
721+ million Domains tracked
2,864+ TLDs tracking
11+ years of data crawling


  • Discover all domain names associated with an individual or an organization. Find connections between various domains, individuals and organizations.

  • Search results can be filtered based on registration or expiration date. For example, if you want records only within the last year, you can do that.

  • You may search by specific attributes in the domain’s WHOIS record. For example, search by registrant email address or name.

  • Get consistently formatted and structured WHOIS information for easy comparison with your existing databases.

  • Get Current as well as Historic Reverse WHOIS data.

  • Result options include popularly used Extensible Markup Language (XML) and JavaScript Object Notation (JSON).

  • Your search term can be an exact or a fuzzy match. For example, you may search for any registrant name that starts with the term “John” or any registrant email address that contains the term “xyz.”

  • With regularly updated WHOIS data, you’re sure to get only the latest information.

Practical usage

Protection for brands

Protection for brands

Brand protection professionals can safeguard their crown jewels by alleviating potential trademark infringements with reverse WHOIS data. Reverse WHOIS API catches domain lookalikes or copycats.

Cybersecurity enhancement

Researchers can rely on Reverse WHOIS API in combination with a WHOIS history viewpoint to investigate and eventually thwart cybercrime. Meanwhile, integration into antimalware solutions can detect spam, malicious links, attack attempts, and other misdeeds.

Cybersecurity enhancement
Online fraud detection

Online fraud detection

Reverse WHOIS API helps payment processors, banks, and other financial institutions prevent transaction fraud. Website owners and administrators can use it to scout for legitimate business and partnership opportunities using the contact details that domain owners reveal in their WHOIS records.

Policing the Web

Reverse WHOIS API or Reverse WHOIS Search is an investigation must-have for law enforcement agents who wish to map out attackers’ infrastructure. Find all domains, websites, IP addresses, and more details connected to a crime or criminal with the tool’s help.

Policing the Web
Market research

Market research

Reverse WHOIS API benefits business owners on the lookout for expansion. Use it to find new customers, too, through the contact details you can get from the WHOIS database.

A single unique WHOIS record identifier lets you find all related domain names and more with our new Domain Research Suite (DRS) dashboard.

Fast, intuitive and responsive

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Reverse WHOIS Search | Domain Research Suite | WhoisXML API
Reverse WHOIS API | WhoisXML API

Get 500 free API credits. No credit card required.

Get started

Enterprise API Packages

WhoisXML API offers annual subscription packages for all of its APIs. Your number of queries determines how much you need to pay each month, giving you a chance to allocate resources if you’re on a tight budget.

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