Subdomain Checker

Discover subdomains for any domain using certificate transparency logs and DNS lookups.

Enter a domain to get started.

About Subdomain Checker

This tool discovers subdomains for any domain by combining two data sources: certificate transparency (CT) logs, which record every publicly-issued TLS certificate, and DNS brute-force lookups against a list of common subdomain prefixes. Together they surface subdomains you may not know exist.

How to Use

Enter Domain: Type a domain name without protocol, e.g. google.com.
Search: Click "Find Subdomains" to query certificate transparency logs and run a DNS lookup.
Review Sources: Check the CT / DNS / BOTH badge next to each result to gauge reliability.
Copy: Use the copy icon on any row, or "Copy All" to grab the full list at once.

Understanding Results

Each subdomain is tagged CT, DNS, or BOTH to show where it was found.

Buy Me a Coffee