Free Sub Domain Finder v2.0

Subdomain Finder: Find All Subdomains
of a Domain Online

Check subdomains of a domain instantly with our professional discovery tool. Identify hidden assets, legacy dev environments, and map your digital footprint securely.

Target Entity

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Unique Hosts

Hostname	Verification	Resolved IP	Lat. / Ports

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Show Subdomains of Domain

Instantly retrieve hostnames linked to root domains via public SSL transparency logs. Perfect for initial recon.

Get Subdomain of a Domain

Map out development, staging, and API endpoints often overlooked by IT teams but visible to OSINT engines.

Sub Domain Finder C99

Reliable discovery methodology inspired by legacy security frameworks, optimized for modern cloud infrastructure.

Advanced Strategies to Find All Subdomains of a Domain

Organizations today operate across multiple cloud providers and hosting platforms. This complexity makes it difficult to list subdomains of a domain manually. A professional sub domain finder is essential to ensure that no "shadow IT" exists within your perimeter.

Understanding Attack Surface Management

To effectively check subdomains of a domain, one must understand that assets are often created for temporary projects but never decommissioned. These orphaned subdomains are prime targets for subdomain takeovers.

Shadow Assets: Marketing pages or test portals created by non-IT staff.
CNAME Dangling: DNS records pointing to expired cloud instances.
Third-Party Exposure: Subdomains used for helpdesks, status pages, or email automation.

How to Get All Subdomains From a Domain Online

Our engine uses Passive OSINT, meaning we don't touch the target's servers. By querying the global certificate transparency infrastructure, we can get all subdomains of a domain online with 100% stealth. This is the preferred method for red-teaming and ethical hacking where noise must be minimized.

Passive vs. Active Enumeration

Active enumeration involves sending DNS queries directly to recursive or authoritative name servers. While thorough, it can be slow and easily blocked. Our subdomain finder focuses on passive data, allowing you to find all the subdomains of a domain in a fraction of the time by leveraging indexed historical data.

Frequently Asked Questions

How can I check subdomains of a domain for free?

Use the search tool above. It allows you to enter any root domain and instantly check subdomains of a domain for free. The tool queries multiple OSINT sources to provide an accurate list without requiring any software installation.

Is this the best sub domain finder online?

We aggregate data from several high-authority sources including CRT.sh and global DNS archives. This multi-vector approach makes it one of the most comprehensive ways to get all subdomains from a domain available to the public.

What are Certificate Transparency (CT) logs?

CT logs are public ledgers that record every SSL/TLS certificate issued by Certificate Authorities. By monitoring these logs, we can show subdomains of domain hostnames as soon as a certificate is created, even before they are actively used.

Can this tool find "hidden" or internal subdomains?

It can find any subdomain that has ever had a public SSL certificate or a public DNS record. While it cannot "guess" internal-only hostnames that have never touched the public internet, it is highly effective at finding all subdomains of a domain that have a footprint.

What is a Subdomain Takeover?

A takeover occurs when a subdomain points to a service (like an S3 bucket or GitHub Page) that no longer exists. An attacker can claim that service name and host their own content on your subdomain. You should always list subdomains of a domain and verify their targets to prevent this.

Is it legal to find all the subdomains of a domain?

Yes. The information retrieved by our subdomain finder is public knowledge. Querying public logs and DNS records is a standard part of ethical security research and OSINT investigation.

Subdomain Finder: Find All Subdomains of a Domain Online