Bulk Whois Lookup

Bulk WHOIS Lookup: Tools and APIs

The World Wide Web is a vast and intricate network of websites, each with its own domain name. To keep track of domain ownership and related information, the WHOIS database was created. WHOIS is a system that provides information about registered domain names, including the domain’s owner, registration date, and contact information. Using a bulk whois lookup is essentially doing thousands of these whois checks at once.

For individuals, businesses, and organizations looking to gain insights into domains on a large scale, “Bulk WHOIS” is the go-to solution. In this article, we’ll delve into what WHOIS is, explain what Bulk WHOIS searches are (cached or live whois), explore the tools available for these searches, and discuss the difference between using tools and APIs for Bulk WHOIS as a developer.

In short, the major difference is that one is a tool non-developers use, while the other helps developers build those tools.

Understanding WHOIS

WHOIS (pronounced as “who is”) is a protocol used to query databases and obtain information about domain names, IP addresses, and autonomous system numbers (ASN) used on the Internet. This information typically includes:

  1. Domain Ownership: The name and contact details of the domain registrant, which can be an individual or an organization.
  2. Registration Date: The date when the domain was initially registered.
  3. Expiration Date: The date when the domain registration is set to expire.
  4. DNS Servers: The authoritative name servers responsible for handling DNS queries for the domain. (shown as NS – Nameservers)
  5. Registrar Information: Details about the domain registrar that registered the domain.
  6. Status Information: Indicates if the domain is active, pending transfer, or has expired.
  7. Contact Information: Administrative, technical, and billing contacts associated with the domain.

Bulk WHOIS Lookup

Bulk WHOIS searches involve querying the WHOIS database for information on multiple domain names simultaneously. This is especially useful for various purposes, including:

  1. Cybersecurity: Identifying potentially malicious domains or tracking down the source of cyber threats.
  2. Brand Protection: Monitoring domain registrations to prevent brand abuse, such as domain squatting.
  3. Market Research: Gathering data on competitors’ domains and their online presence.
  4. Domain Portfolio Management: Managing a large portfolio of domains efficiently.
  5. SEO: Looking for potential domain names you might acquire, get backlinks from, or investigate competition
Bulk domain checker example
Bulk domain checker example

Tools for Bulk WHOIS Lookup

Several tools are available for conducting Bulk WHOIS searches. These tools allow users to enter a list of domain names and retrieve the associated WHOIS data in a convenient format. Some popular Bulk WHOIS tools include:

  1. Free online tools: there are free tools that allow bulk whois searches, but they seldom work or provide limited TLD support
  2. Paid solutions: Paid solutions work well, but can be expensive for amateurs, hobbyists or startups
  3. Software: There are older solutions that you have to install on your Windows or Mac OS

In all honesty, there are not that many bulk whois tools. One of the reasons is that it’s they are not that easy to build, and users aren’t ready to pay for them. The few free tools that are out there are not working properly. We are left with Whois APIs where we need to hire a developer to operate them.

Bulk WHOIS Searches with APIs

Developers often require programmatic access to WHOIS data for integration into their applications. To facilitate this, WHOIS providers offer APIs (Application Programming Interfaces) that allow developers to automate the retrieval of WHOIS data in real-time. Here are the key differences between using tools and APIs for Bulk WHOIS searches:

Bulk whois tool servers
Image by benzoix on Freepik
  1. Automation: APIs are designed for programmatic access, enabling developers to integrate Bulk WHOIS searches seamlessly into their applications. Tools typically require manual input and may not be suitable for large-scale automation. Imagine checking millions of domain names.
  2. Real-time Data: APIs provide real-time access to WHOIS data, ensuring that the information is up-to-date. Tools may rely on cached data, which can become outdated.
  3. Customization: Developers can tailor API requests to their specific needs, retrieving only the data they require. Tools may have limitations in terms of customization, TLD support and so on.
  4. Scalability: APIs are built to handle large volumes of requests efficiently, making them suitable for high-throughput applications. Tools may be limited in their capacity to handle bulk requests. Especially free tools.

Bulk whois in short

Bulk WHOIS searches are a valuable resource for individuals, software companies, and developers seeking to gain insights into domain ownership and related information on a large scale. While tools are suitable for manual or occasional use, APIs provide developers with the power of automation, real-time data access, and customization options, making them the preferred choice for large-scale and time-sensitive applications.

Whether you’re a cybersecurity expert, a brand manager, or a developer, understanding how to utilize Bulk WHOIS searches effectively can be a valuable asset in today’s digital landscape.

WhoAPI can assist with our Whois API and you can get free 10,000 API requests today. On the other hand, if you think we should build a bulk Whois checker, we think that you are in a better position to do that.


Goran Duskic has been the Founder and CEO of WhoAPI Inc. since 2011, a company that specializes in developing APIs, including the well-known Whois API. He started his career in internet entrepreneurship in 2006 and has co-founded several online businesses, including a web hosting company that he later sold. Goran's work primarily involves creating practical API solutions to meet technological needs.