Domains & Subdomains Discovery Service | WhoisXML API

Domains & Subdomains Discovery Service allows you to identify all domains and/or subdomains connected by hostname terms

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500 free API requests. No credit card required.

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

Our Domains & Subdomains Discovery Service product line includes:


Just take a hostname search string and instantly get a list of connected domains and subdomains. Get more accurate results according to your needs using advanced search options.

Domains & Subdomains Discovery Lookup | WhoisXML API
Domains & Subdomains Discovery API | WhoisXML API


With one API call, you will get a list of all related domains and subdomains that contain specified hostname strings.

Benefits of Domains & Subdomains Discovery Service

  • Comprehensive and accurate

    Domains & Subdomains Discovery Service supports nearly every top-level domain (TLD), now numbering in excess of 7,596.

  • Up-to-date

    All of the service’s search results are the product of 14+ years’ worth of data crawling and aggregation with daily updates. Our database is expanding at a rate of 1M newly discovered subdomains per day.

  • Well-Parsed

    We normalize and parse our data to give users results in ready-to-use Extensible Markup Language (XML) and JavaScript Object Notation (JSON) files integrable with any business process.

Practical usage

Prevent Online Counterfeiting

Collate comprehensive lists of domains and subdomains possibly connected to ongoing counterfeiting campaigns. Use the campaign’s target brand or company name as a search string on Domains & Subdomains Service to find web properties that can serve as potential vehicles for the threat.

Protect Your Brand

Find out if threat actors could be spoofing your brand or company through look-alike websites and web pages. Use your brand or company name as a search string to compile a list of web properties that may not be under your organization’s control to ensure they are not used to host phishing or pharming sites or pages.

Uncover DNS Trends

Get the lowdown on emerging domain registration trends that could help you uncover yet-unreported threats or business opportunities.

Enhance Service Discovery

Learn more about your clients’ or partners’ services by looking into their existing subdomains. Subdomain details can also allow you to monitor the competition or improve your software-as-a-service (SaaS) offerings to get a bigger market share.

Domains & Subdomains Discovery Service | WhoisXML API

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