SSL certificate expiry monitoring — questions, answered.

Sign up for a free Monitor SSL Certificates account, add the hostnames you want to watch, and our SSL certificate expiry monitoring tool connects on port 443 every 12 hours to read the certificate chain. Whenever the issuer, valid-from, valid-to, signature algorithm, or SAN list changes, we log the event. As the notAfter date approaches we send SSL certificate expiry alerts by email at 30, 15, 7, 1, and 0 days before the expiry date so you have time to renew.

An expired TLS certificate drops HTTPS back to HTTP, browser warnings like NET::ERR_CERT_DATE_INVALID scare users away from your checkout, search engines demote your rankings, and payment APIs return errors. Monitoring SSL certificate expiry turns the only predictable web-platform outage into a non-event — your team gets a heads-up days before the expiry date instead of waking up to a broken site. It's also the simplest SSL certificate expiry vulnerability fix available: a recurring automated check that costs less than a minute of engineering time per year.

Use a dedicated SSL certificate expiry monitoring tool like Monitor SSL Certificates: add each hostname you own, pick the alert cadence (we default to 30 / 15 / 7 / 1 / 0 days), and let an external system poll the certificate on a fixed schedule. For internal certificates behind a firewall, run a lightweight agent on the same network so the monitor can reach port 443 without going through the public internet. For public certificates, no agent is required — just point us at the hostname.

SSL certificate expiry alerts go out at 30 days, 15 days, 7 days, 1 day, and on the day of expiry. One alert per stage, deduplicated across the team, sent via email.

Free, forever. Monitor SSL certificate expiry automatically for up to 10 hostnames at no cost — no credit card, no trial expiry, no paid tiers.

Internal certificate monitoring requires a lightweight agent installed on your network so the SSL certificate expiry checker can reach port 443 from inside your firewall. Public certificates are fully supported on the free plan with no agent.

Yes. We notify you whenever a new certificate is issued for one of your monitored domains — even if you didn't request it — so you can spot a fraudulent issuance before it causes damage.