Subdomain finder
Subdomain finder
List the subdomains of a domain that appear in public Certificate Transparency logs, and optionally check which of them still resolve. It turns up forgotten staging sites, old services and aliases left pointing nowhere.
We check from the outside, the way visitors see your site, and keep a simple log of sites checked. Privacy policy.
How it works
What this checks
- Certificate logs Every name found in certificates issued for the domain, from public Certificate Transparency logs.
- Passive by design Only the logs and public DNS resolvers are contacted, never the subdomains themselves.
- Live check Check the option to resolve up to 50 names and see which still have addresses.
- Dangling aliases Aliases (CNAMEs) that point at names which no longer exist, a common route to a subdomain takeover.
- Limits Names that never had a public certificate do not appear, so treat the list as a starting point, not a full inventory.