Certificate Transparency Search

Certificate Transparency Search queries the public CT logs (via crt.sh) to return every publicly-trusted TLS certificate that has ever been issued for a domain. Since 2018, Chrome and other major browsers refuse to trust any publicly-issued certificate that is not logged, so CT is effectively a global, tamper-evident ledger of the entire public TLS ecosystem — a gold mine for reconnaissance, incident response, subdomain discovery, and detection of unauthorized certificate issuance.

For each certificate we show the common name, issuing CA, validity window, the number of Subject Alternative Names, and a direct link to the full record on crt.sh. Because SANs are indexed, requesting a domain with 'include subdomains' will surface hostnames you may have forgotten about — dev, staging, internal-*.example.com, one-off marketing subdomains — anything that has ever received a certificate. That's often the fastest way to enumerate the true attack surface of a target.

Combine CT Search with our CAA Lookup (which CAs are allowed to issue) and SSL Checker (what's live right now) for a complete picture of your TLS story. Security teams use it to spot mis-issuance immediately; DevOps teams use it to inventory certificates before a CA migration; bug-bounty hunters use it to discover overlooked hosts.