Free tool
Certificate Transparency lookup
Enter a domain to see the TLS/SSL certificates issued for it in public Certificate Transparency logs - and the subdomains those certificates reveal.
Frequently asked questions
What is Certificate Transparency?
Certificate Transparency (CT) is a public, append-only log of almost every TLS/SSL certificate issued on the web. Anyone can search it to see which certificates exist for a domain - which is how you spot an unexpected or mis-issued one.
How can I find all subdomains of a domain?
Certificates often name the exact hostnames they cover, so the CT logs reveal many subdomains. Enter a domain here and we list the unique hostnames seen in its certificates - useful for spotting forgotten or exposed subdomains.
Where does this data come from?
From crt.sh, a free public Certificate Transparency search service. We only read public log data; we don't connect to your site.