Bulk WHOIS Lookup of 500K domains simultaneously | WhoisXML API

Bulk WHOIS Lookup: Get the Registration Data of Thousands of Domains in One Go

Get the registration details of up to 500,000 domains at once to speed up your investigation or research. Test Bulk WHOIS Lookup now. Download our product sheet to learn more.

What is a bulk WHOIS lookup?

A bulk WHOIS lookup is a means to get details that include registrant name, organization, contact email address, and much more with a single query. Just upload a comma-separated values (CSV) file containing the list of domains you want information on or copy and paste the list into the input box and wait for your results.

Our bulk WHOIS lookup tool is:

  • Always on

    Bulk WHOIS Lookup is a web-based service that you can access anytime you need to query a list of domains for ownership data. All you need is a WhoisXML API subscription to get the results you require.

  • Backed by one of the biggest WHOIS databases

    Our bulk WHOIS lookup tool pulls data from a domain database that contains more than 21.0 billion WHOIS records that cover 7,596+ top-level domains (TLDs).

  • Robust

    Every bulk domain lookup you make is sure to get the latest registrant information as our WHOIS database gets daily updates. That assures you of relevant and timely data for your business needs.

  • Flexible

    Bulk WHOIS Lookup lets you choose between uploading a CSV file or copying and pasting your list into the interface when making queries.

Practical usage



  • Look up all domains related to an email or IP address when investigating a potential crime or an ongoing attack with our bulk domain WHOIS tool.
  • Know everything there is to know about a domain of interest, including the registrant’s name, organization, address, and more, when you’re building an attack profile with a simple bulk domain lookup.

Domain research and monitoring

  • Follow every move competing domainers make. The list of domains that you get from a bulk domain lookup should clue you into emerging trends you may be missing out on.
  • Track modifications made to your domain portfolio with a bulk domain WHOIS query. Some of them may have been unauthorized and need to be addressed immediately.
Domain research and monitoring
Marketing and sales

Marketing and sales

  • Ensure you don’t miss out on any online infrastructure changes your customers make. Constantly update your contact list with bulk WHOIS lookups.
  • Get to know your clients and stakeholders better by looking at their digital footprints. You may find untapped sales opportunities with deeper digs via bulk domain lookups into their lines of business.

Brand protection and fraud prevention

  • Make sure you are dealing with legitimate users from your client list through a bulk domain lookup. Compare their credentials with those of their supposed organizations that you keep on record.
  • Keep your contact list up-to-date with regular checks on our bulk domain WHOIS tool that’s updated daily.
Brand protection and fraud prevention

Integrate Bulk WHOIS API for faster results

Bulk WHOIS API gives the same results but is integrable into existing systems and solutions so you can get what you’re looking for faster and use the information immediately. Sample codes for the commonly used languages (C#, JavaScript, PHP, etc.) are available.

Learn more about Bulk WHOIS API