Subdomains Lookup API | Get a list of subdomains | WhoisXML API

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.

Get started

500 free API credits. No credit card required.

2.3 Billion+Subdomains
1 Million+Subdomains discovered daily
52,000+Satisfied customers
14+Years of data crawling


  • 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

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 Make a quick self-assessment to uncover all potential weak points, outdated software, or misconfigurations.

Explore your web infrastructure
Enrich marketing research

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.

Integrate additional data into your products
Subdomains Data Feed

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.

Request a Quote
Subdomains Lookup API | WhoisXML API

Get 500 free API credits. No credit card required.

Get started

Premium API Services

Our APIs are available in an enhanced version that offers better performance with a dedicated load balancer and a premium endpoint to enable faster throttling for large-scale API deployments.

Learn more

Enterprise API Packages

Get the benefits of accessing up-to-date subdomain data along with all other sources of domain and IP intelligence. Subscribe to an annual plan that fits your business requirements now.

Learn more