Subdomain Finder
Discover hidden, forgotten, or misconfigured subdomains to reveal critical vulnerabilities. Our Subdomain Finder uses passive and active methods with real-time validation and intelligent filtering for clean, actionable results.
Use it to scan at scale, automate discovery across environments, and map your attack surface in depth with multi-method enumeration, reverse DNS lookups, WAF detection, hidden files discovery, and more.
- Scan type
Light scan
Discover hidden, forgotten, or misconfigured subdomains to reveal critical vulnerabilities. Our Subdomain Finder uses passive and active methods with real-time validation and intelligent filtering for clean, actionable results.
Use it to scan at scale, automate discovery across environments, and map your attack surface in depth with multi-method enumeration, reverse DNS lookups, WAF detection, hidden files discovery, and more.
Built for integrated discovery workflows
The Subdomain Finder doesn’t just give you lists of hostnames. It provides the visibility needed to assess risk and secure assets you or your security team didn’t know existed.
It’s fully integrated into our cybersecurity toolkit to help you find hidden web content quickly and follow up with focused validation.
Use it in your early recon stages to expand the attack surface. Then, dig deeper with the Port Scanner or Network Scanner for vulnerability assessments, compliance checks, or highly-focused penetration testing.
Map your real attack surface
Many vulnerability scanners and subdomain enumeration tools work only with the main domain or known subdomains. Our Subdomain Finder combines OSINT techniques, DNS scraping, recursive brute forcing that exposes deeply nested assets, and API integrations with large datasets. You will see exactly how each subdomain was found, with zero setup and no CLI complexity.
Get context-rich results
Each discovered subdomain includes relevant metadata like DNS records, web server and web technologies, IP addresses of the found domains, WHOIS and OS information, and HTTP status. Use this data to prioritize subdomains for vulnerability assessment or to identify targets for manual exploitation during penetration testing, or validate policy compliance.
Customize your scan for deeper results
Some of the most valuable subdomains have non-obvious names. Find them with wordlists aka customizable lists containing thousands of potential names. Use our built-in ones, or upload your own for a highly targeted scan. Plus, localized wordlist enhancements add linguistic variation that boosts discovery rates across global domains.
Connect your tools, not just your data
Move swiftly from discovery to validation. Use your newly-found subdomains immediately with the Port Scanner, Website Scanner, URL Fuzzer, or launch proof-driven network penetration tests. Every scan backs up more informed vulnerability assessments and makes your recon workflows faster and highly accurate.
Get actionable results with built-in automation
Use Pentest Robots with automated, deep port scanning and service discovery after each subdomain scan. Queue them for pentesting follow-ups, power scheduled scans or asset tracking, gather proof with screenshots, and automate discovery workflows that would take hours manually. Plus, built-in integrations push results instantly via email, Slack, or webhooks to keep your team in sync.
Gain visibility into unknown subdomains
Our Subdomain Finder surfaces assets your team didn’t know existed, from forgotten dev environments to shadow IT or staging systems, and instantly flags subdomains that may be unpatched or exposed to critical vulnerabilities like Log4Shell. Use these insights to expand attack surface coverage, guide focused penetration testing across hidden infrastructure, or validate compliance.
Sample Subdomain Finder report
List of all subdomains found during the scan, including DNS resolutions.
How the Subdomain Finder works
The Subdomain Finder is fully hosted online and uses a multi-layered discovery process to uncover as many subdomains as possible, with minimal noise.
Run manual or scheduled scans, from your dashboard or via API, or chain it to multiple other tools with Pentest Robots. Combine scanning methods to balance stealth and performance, then integrate the results directly into your information gathering workflow.
Multi-method enumeration
Our Subdomain Finder uses a wide range of sources and techniques, including public DNS records (NS, MX, TXT, AXFR), SSL certificates, HTML links, and search engine queries to perform subdomain discovery. For dictionary-based enumeration, it uses built-in wordlists, but you can also upload your own. It also applies word mutation techniques to surface subdomains other tools typically miss. The Subdomain Finder also runs reverse DNS and CNAME lookups, and generates smart variations of discovered names.
Real-time validation and intelligent filtering
Our Subdomain Finder validates results in real time through DNS resolution, and automatically filters our unresponsive, unresolved, or duplicate entries. Unlike typical recon tools out there, our Subdomain Finder doesn’t fully rely on cached data, instead it pulls fresh, real-time records for every scan.
Localized wordlist enhancements
The Subdomain Finder also adapts subdomain enumeration wordlists based on top-level domain(TLD) language, using our proprietary algorithm. This adds linguistic variation that boosts discovery rates across global domains.
Recursive brute-force discovery
This Subdomain Finder launches a follow-up search each time it discovers a new subdomain, using specialized lists for sub-subdomains. This recursive flow uncovers deeply nested assets that static brute-force scans miss
Faster, smarter DNS enumeration
DNS-based tests use an upgraded wordlist built from the 5000 most common subdomain names, researched and validated by our security team. This improves discovery accuracy, especially in deep scans.
See the Subdomain Finder in action
How our Subdomain Finder is different
Part of a comprehensive offensive security workflow
Unlike standalone tools, the Subdomain Finder works inside a full offensive cybersecurity product. It boosts your recon when you use it with the Port Scanner or Website Scanner. It also makes working together easy with shared workspaces . You can integrate everything with your pentesting stack via API, or automate entire workflows with Pentest Robots.
Flexible, deeper discovery
Use Certificate Transparency logs, SSL certificates, Google search, and HTML links to quickly uncover hidden subdomains at scale. Fine-tune with DNS brute-force techniques and complex alterations. Improve results with IP, DNS, or HTTP metadata, and go deeper with WHOIS info or custom wordlists.
Fast, clean, exportable results
Export in CSV, JSON, XLSX, and more. Filter and reuse subdomains for follow-up assessments, evidence gathering, or report building without messy parsing.
Made for professionals who need to scale subdomain finding
Security consultants
Speed up early-stage reconnaissance across multiple client domains with accurate, real-time subdomain discovery. Our Subdomain Finder helps you uncover exposed services and misconfigured systems, with no setup or manual parsing required. Perfect for scoping and automating recon across multiple environments.
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Internal security teams
Continuously monitor your organization’s attack surface to identify new, forgotten, deprecated, or shadow assets and map the security risks they create. Use our Subdomain Finder in recurring audits, compliance checks, or web app pentesting, so nothing slips past your defenses.
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Managed Security Providers (MSPs)
Run scalable, automated subdomain scans across customer environments with the built-in scheduler, API, or chain them with multiple other tools using Pentest Robots. Integrate the results into your playbooks and deliver ready-to-share recon insights in minutes, without any CLI tools.
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Customer reviews
Excellent with reconnaissance info, external scans. The scans run quickly and the dashboard is easy to use. I like the attack surface feature. Organizing your scans and data is very simple to follow. Being cloud-based, you can get to the tools from anywhere without lugging around a dedicated device. The ability to generate and customize reports is very helpful.
Dr. Patrick Johnson
Business Owner at True North Consulting Group
Industry
IT & Services
Subdomain Finder FAQs
What is a subdomain finder?
A subdomain finder is a reconnaissance tool used in penetration testing to discover subdomains associated with a target domain. These subdomains often expose hidden, forgotten, or development systems and misconfigurations attackers can exploit. The Subdomain Finder from Pentest-Tools.com uses passive and active methods to find subdomains quickly, with no setup required.
What are subdomains?
A website subdomain is a domain subordinated to another domain(e.g. blog.domain.com or support.domain.com). If you are pentesting websites, it’s important to know which subdomains are exposed to potential malicious hackers through vulnerabilities, misconfigurations, and business logic security issues. By knowing each subdomain's purpose, you can prioritize business-critical assets for further investigation.
How do I find all subdomains of a domain?
To find all subdomains of a domain, use a subdomain finder that combines multiple techniques. Our tool queries public DNS records, search engines, certificate transparency logs, and performs brute-force enumeration with custom or built-in wordlists. For deeper coverage, enable recursive brute-force discovery to uncover nested and obscure subdomains.
What makes this subdomain scanner different?
Unlike standalone scripts, our subdomain scanner is fully hosted, it requires no setup, and is part of an entire ecosystem of tools and features you can even combine into automated testing sequences. It offers real-time DNS validation, reverse DNS lookups, full subdomain enumeration, SSL certificates search, external APIs search, customizable wordlists, seamless export options and the list goes on. You get clean, actionable results for asset discovery, attack surface mapping, plus embedded automation.
What’s the difference between the free and paid Subdomain Finder?
The free version gives you fast, no-setup subdomain lookup, which is great for quick recon against a domain name and exposed services discovery (like open ports or virtual hosts).
The paid version unlocks full-spectrum recon: deeper scans, reverse DNS checks, custom wordlists, recursive enumeration, enriched DNS metadata, and export-ready reports for follow-up work. Plus access to a much larger part of our product, depending on your pricing plan.
How accurate are the results?
The tool combines multiple sources and applies real-time DNS resolution to validate findings. It filters duplicates and unreachable records automatically, ensuring high accuracy and relevance in every subdomain lookup.
Can I automate subdomain scans?
Yes. Use our REST API or Pentest Robots to schedule recurring subdomain searches, chain them with other tools, and receive notifications in your preferred channel (email, Slack, webhooks).
Is this tool better than free subdomain finders?
Free subdomain finder tools often use limited data sources, cache results, and don’t offer real validation. Our Subdomain Finder delivers complete, fresh scans with exportable results and deeper integrations that are designed by our security researchers for real-world penetration testing scenarios.
When should I use the Subdomain Finder in my workflow?
Use it at the very start of your information gathering phase to map all potential entry points, especially those not linked or indexed. It sets the stage for deeper vulnerability assessment and validation.
What’s the difference between a subdomain lookup and a subdomain scan?
A subdomain lookup typically checks for known records via passive methods. A subdomain scan, like the one from Pentest-Tools.com, goes deeper, and it combines passive OSINT sources with active DNS brute-force to enumerate subdomains of a domain, even the ones not indexed or public.
Can I use Subdomain Finder to check subdomains without installing anything?
Yes. Our subdomain checker is cloud-based, fully hosted, and requires no installation or configuration. Just log in, run the scan, and find subdomains of a domain instantly. It’s ideal for consultants, MSPs, security researchers, or internal teams who need to assess security risks quickly and demand repeatable results.
Is this tool useful for subdomain search at scale?
Definitely. If you need to perform subdomain search across multiple targets, the Subdomain Finder supports bulk scans, exports grouped by root domain, and automation via API or Pentest Robots. It’s built for consultants, MSPs, and security teams managing large scopes.
Can I find all subdomains even if they’re not publicly indexed?
Yes. The tool uses recursive brute-force, DNS record scraping, and certificate analysis to find all subdomains of a given domain, including those that don’t appear in search engines or are not externally linked. This helps expose hidden systems that might still be live.
Can I integrate subdomain results into my testing workflow?
Absolutely. You can export subdomain enumeration results in JSON, CSV, PDF, HTML, or XLSX or include the most interesting scan results into editable DOCX reports, then feed the data into other tools from our product, or start scheduling follow-up scans, depending on your use cases. It’s one of the most efficient ways to find subdomains and act on them fast.
Can I use my own wordlist for subdomain enumeration?
Yes. The Subdomain Finder lets you upload custom DNS wordlists to find a list of subdomains that are unique to your target. You can also choose to include unresolved subdomains or focus only on live systems.
What can I do after I find subdomains?
Once you get all subdomains of a domain, use them to identify exposed services, deprecated systems, or vulnerable entry points. Follow up with the Port Scanner, the Website Scanner, or launch full vulnerability assessments. These findings are especially valuable for penetration testers, security teams, and MSSPs who need to maintain compliance, or asset discovery during audits.
These findings are especially valuable for penetration testers, security teams, and MSSPs who need to maintain compliance, or asset discovery during audits.
What kind of wordlists can I use?
You can use our curated DNS lists or upload your own. This helps find company-specific or obscure subdomains.
Can I integrate the tool with my recon automation?
Yes. You can use the REST API to run scans, retrieve results, and chain with other tools like the Port Scanner and the Website Vulnerability Scanner.
How accurate are the results?
We aggregate multiple sources and use smart deduplication to reduce noise. Each result includes DNS metadata to help you validate it fast.