What this tool shows
An expired TLS certificate throws a browser warning that scares users away and can take a service offline. This checker reads the certificate the site actually serves, over a live handshake, and shows the exact expiry date, the days remaining, the issuer, and the certificate chain. It is the reliable way to confirm how long you have before you need to renew.
Frequently asked questions
How early should I renew?
Renew at least two weeks before expiry to leave room for propagation and any issues. Many certificates, like those from Let's Encrypt, are valid for 90 days and are meant to auto-renew around 30 days out.
Why does this differ from what I see elsewhere?
Some tools read certificate transparency logs, which show certificates that were issued, not the one currently served. This checker reads the live certificate over a real handshake, so it reflects what visitors actually get.
My certificate auto-renews. Do I still need to check?
Yes. Auto-renewal can quietly fail if a validation record breaks or a hook errors out. Confirming the served certificate and its expiry is the only way to be sure the renewal actually took effect.