Free checker
See the certificate your server is presenting
We connect to the server the way a browser does and read its live certificate, its trust chain, and the registrar expiry date. Nothing is stored unless you start monitoring.
Why this date can differ from my registrar
The certificate date is how long the TLS certificate is valid for, and short-lived certificates renew every few days. The registrar date is when your domain registration itself ends. Both matter: an expired certificate breaks HTTPS, and an expired domain takes the whole site offline.