List the subdomains of a company’s website

With one API call, instantly get a list of all subdomains related to a given domain name to reveal a company’s entire web infrastructure. Use it to identify and fortify potential vulnerabilities.

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500 free API credits. No credit card required.

9.6 Billion+Subdomains

15 Million+Subdomains discovered daily

52,000+Satisfied customers

15+Years of data crawling

Benefits

Our subdomains lookup intelligence reveals every subdomain a domain name has, including when these were last modified.
Query results with both parsed and raw fields are returned in popular formats—Extensible Markup Language (XML) and JavaScript Object Notation (JSON)—allowing for easy integration.
Our Subdomains Lookup API works for nearly all top-level domains (TLDs).
Use Subdomains Lookup API in addition to Domain Research Suite to correlate WHOIS records with subdomain intelligence when doing in-depth investigations and research.

Practical usage of a subdomain list

Improve cybersecurity

Know all your network’s weakest points to fortify your cyber defense. Identifying all your subdomains and making sure these are sufficiently protected at all times is essential to optimize your cybersecurity posture.

Enhance penetration testing

Finding subdomains is an important step in the information gathering phase of a penetration test. Ensure that none of your unused or forgotten subdomains are left dangling, making them easy targets for attackers to gain unauthorized entry into your network.

Expand blacklists

Only by examining even the subdomains of suspicious sites can you truly stay protected from all kinds of possible harm. Include every malicious subdomain (even those not identified as indicators of compromise [IoCs]) in your blacklists for greater security.

Explore your web infrastructure

Digging as deep as possible into your web infrastructure lets you evaluate all connected systems for vulnerabilities. Make a quick self-assessment to uncover all potential weak points, outdated software, or misconfigurations.

Enrich marketing research

Screen your competitors' subdomain additions to understand their web infrastructure better.

Identify possible business development opportunities as subdomains can reveal the types of digital business partners a prospect is currently working with.

Integrate additional data into your products

Build your own products and enrich them with our high-value data. Every API response is returned in JSON and XML formats, which is compatible with popular coding languages.

Get access to the biggest subdomain database

Our database comes in the form of daily and monthly comma-separated values (CSV) files and MySQL dumps. Get the most accurate and up-to-date subdomain data for easy integration into your platform.

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Kim Kok

Vice President

Core4ce

“We want to provide all Cyberscape users the ability to integrate relevant data for their cyber threat investigations. WhoisXML API provides unique data that will be helpful to the cyber threat investigation community, allowing analysts to shorten the cycle of understanding and mitigating threats.”

Rahul Madduluri

Co-Founder and CTO

Doppel

“We did trials with WhoisXML API to make sure the data was truly resulting in successful takedowns. We were able to consistently discover and mitigate real threats as a result of using the products.”

WHOIS / WHOIS History

DNS / DNS History

IP Geolocation / IP Netblocks

Domain Research Suite (DRS)

Domain/WHOIS

DNS/IP

Intelligence

Other

Domain/WHOIS

DNS/IP

Intelligence

Other

Domain/WHOIS

DNS/IP

Intelligence

Other

Domain Research Suite (DRS)

Research

Monitoring

White-Label

Predictive Threat Intelligence Feeds

Internet Infrastructure

Enterprise API Packages

Security Intelligence (SI) Suite

List the subdomains of a company’s website

Benefits