TLS certificates expire. When they do, browsers show scary warnings and most visitors leave. The fix is usually renewing the certificate — but only if someone knows it is about to happen.
Why certificates get missed
- Auto-renewal failed silently (common with Let's Encrypt cron jobs)
- A staging certificate was deployed to production by mistake
- A subdomain was added but never included in the cert
- The person who set up HTTPS left the company
What to monitor
At minimum, track days until expiry for every public hostname you care about. Alert at 30, 14 and 7 days so there is time to renew without panic.
Useful details in an alert:
- Hostname the certificate covers (SAN list)
- Issuer and validity dates
- Whether the certificate matches the hostname (CN/SAN mismatch causes errors even when not expired)
One-off vs continuous checks
A free SSL checker is perfect before you onboard a new site or after a deployment. Continuous monitoring catches the certificate that expires on a Sunday when nobody is watching dashboards.
How UpMonix handles SSL
Domain monitors include SSL expiry tracking alongside DNS and registration data. Alerts go through the same communication platform as uptime incidents — email, Telegram, Slack and more — so the right person gets the warning in time.
Start free monitoring and SSL checks are configured automatically for your domain.