SSL Monitoring Best Practices for 2025

It happens to the best of us. You browse to your app on Monday morning, only to be greeted by the dreaded red browser warning: "Your connection is not private." Your SSL certificate expired yesterday.

In 2025, with automated tools like Let's Encrypt becoming standard, manual certificate management should be a thing of the past. Yet, outages caused by expired certs still plague major companies. Here is how to ensure it never happens to you.

1. Monitor the Expiry Date, Not Just Validity

Most basic monitors only check if the certificate is valid right now. That's too late. You need to know when it will expire.

Best Practice: Set alerts for 30, 14, and 7 days before expiry. This gives your team ample time to fix auto-renewal scripts that may have silently failed.

2. Check the Intermediate Chain

A common failure mode is renewing the leaf certificate but serving an old or expired intermediate chain. Browsers might trust it (due to caching), but clean environments and CLI tools will fail.

Pulsx's SSL monitor simulates a fresh handshake to verify the full chain of trust every time.

3. Monitor Mixed Content

Even with a valid certificate, serving HTTP assets on an HTTPS page will cause security warnings. Use a crawler or a dedicated monitor to periodically scan your key pages for mixed content references.

Automation is Fallible

Tools like certbot are fantastic, but cron jobs die, disks fill up, and DNS challenges fail. Monitoring is your insurance policy against automation failures. Don't assume; verify.