SSL/TLS & Transport
medium Severity
Free Check

Certificate Transparency (CT) Logs

Queries crt.sh to verify that all active certificates are logged publicly to detect unauthorized issuance.

Test Your Website for Certificate Transparency (CT) Logs

Run this check along with 90+ automated tests across your domain.

Why It Matters

Certificate Transparency prevents rogue or compromised CAs from issuing invisible fake certificates for your domain.

How We Check This

We query public CT log registries (e.g. crt.sh) and check for Signed Certificate Timestamps (SCTs) in the TLS handshake.

How to Fix & Implement

Copy-paste configuration blocks tailored for your web server or edge proxy.

nginx snippet
ssl_ct on; # or ensure CA submits to CT logs (Let's Encrypt and DigiCert do this automatically)

Frequently Asked Questions

What happens if a certificate is not logged to CT?

Modern Chrome and Safari browsers will reject the certificate and display an untrusted warning.