SSL Checker

The ZeoTools SSL Checker is a bulk TLS certificate checker that opens a real handshake with each domain you paste and reads the certificate the server actually presents. There is no cache and no third-party lookup service in the middle, so what you see is the live certificate as of the moment you pressed the button. Like the rest of our free toolkit, it needs no account and imposes no daily quota.

Days remaining is the number that matters: An expiry date buried in a browser dialog is easy to forget, so this tool puts the countdown in its own sortable column. Sort it ascending and the most urgent hosts rise to the top, with anything already past its date showing a negative count. Certificates with thirty days or fewer are flagged as expiring soon, which is the window in which most automated renewals should already have fired.

Name coverage is checked, not assumed: A certificate can be perfectly current and still be wrong for the address it is serving. Every result is tested against the Common Name and the full subjectAltName list, wildcards included, using the rule that *.example.com covers one label and never the bare apex. A host the certificate does not cover is reported as a name mismatch even when its dates are healthy, and self-signed certificates are called out in the detail column.

What a red row can mean: Unreachable is reported when DNS does not resolve, the port refuses the connection, the handshake times out after eight seconds, or the port simply does not speak TLS. That is a network verdict from our datacenter, not proof that your certificate is broken, so pair it with the Block Checker when a host looks dead here but loads fine for you. For a certificate that is about to lapse, renew first and re-run this page to confirm the new one is really being served.