How to monitor SSL certificate expiry
Expired certificates take sites down and erode trust. Here is how to never be surprised by one again.
An expired TLS certificate makes browsers show a full-page warning and can break APIs that verify certificates. It is one of the most avoidable outages there is.
Know your renewal window
Certificates are valid for a fixed period and are usually renewed automatically — but automatic renewal fails silently. Decide how many days before expiry you want to be warned, and make sure someone acts on it.
Watch every hostname
Your main domain is not the only one that can expire. Apex, www, API subdomains, marketing sites and internal tools often have separate certificates. Monitor each one you serve publicly.
Alert before it expires, not after
UptimeCadet checks the certificate on every HTTPS monitor and warns you before it expires, so you renew while the site is still up.