How to use this tool
Enter a registrable domain and result limit. Cert Spotter certificate-transparency data is deduplicated, wildcard names are normalized, and optional DNS resolution distinguishes currently active hostnames.
Result transparency
Every report identifies completed data sources, unavailable providers, individual findings, coverage, and detailed evidence. Unavailable checks are excluded from scoring rather than treated as passing.
Frequently Asked Questions
What does the Domain & Subdomain Discovery Tool check?
Discover subdomains passively from certificate transparency data and optionally resolve each hostname.
What should I enter in the
Enter the domain or hostname requested by the form without unrelated text, paths, or multiple values.
Are the results live?
The result reflects the data and network response available when the check runs. DNS, HTTP, and certificate information can change later.
What does an unavailable result mean?
An unavailable result means the requested source could not be reached or did not return usable data. It is not automatically a pass or a failure.
Should I rely on this result alone before making changes?
Use the report as a diagnostic reference and confirm important changes with the authoritative provider, hosting panel, or certificate issuer.