In February 2019, Microsoft Teams went down for three hours. Twenty million daily users couldn't access the platform. Meetings were missed. Deadlines were blown. The cause? An expired authentication certificate.
In 2018, Ericsson — a company handling roughly 40% of global mobile traffic — experienced an outage that knocked out 4G and SMS service for 32 million people in the UK. The cause? An expired SSL certificate in software that had been deployed without adequate certificate lifecycle monitoring.
These aren't small companies with amateur IT teams. And yet, they let certificates expire.
Why Certificates Keep Expiring
SSL certificates don't expire without warning. They have a fixed expiry date visible months in advance. The problem isn't that teams don't know — it's that they forget.
The "I'll set a calendar reminder" approach fails because:
- The person who set the reminder leaves the company — and the reminder leaves with them
- Reminders get dismissed and rescheduled — once, twice, then indefinitely
- Multiple domains multiply the failure surface — a freelancer managing 15 client sites has 15 certificates to track
- Certificate authority email notifications go to billing inboxes, get marked as spam, or land in a shared inbox nobody monitors
Google has been pushing for shorter certificate lifespans since 2023. With the industry moving toward 90-day validity periods as the standard, "set and forget" certificate management is functionally dead. You need automated monitoring.
What Happens When an SSL Certificate Expires
The moment a certificate expires:
- Chrome shows a full-page red warning: "Your connection is not private. Attackers might be trying to steal your information from [yoursite.com]."
- Firefox shows: "Warning: Potential Security Risk Ahead"
- 90% of users stop the transaction immediately (WebsitePulse research)
- 85% of shoppers will abandon or avoid sites showing security warnings (BigCommerce research)
- API clients connecting to the expired endpoint receive TLS errors and stop functioning
- Google starts de-indexing or lowering ranking for sites with invalid certificates
For an e-commerce site, this is effectively complete shutdown. For a business application with API dependencies, it can be even worse.
The Right Way to Monitor SSL Certificates
Automated SSL monitoring works by checking the expiry date of the certificate returned by your domain at regular intervals, then alerting you at configurable thresholds before expiry.
A typical alert schedule:
- 60 days before expiry: First notice — plenty of time for scheduled renewal
- 30 days before expiry: Reminder — action should start now
- 14 days before expiry: Urgent — prioritize this
- 7 days before expiry: Critical
- On expiry or failure: Immediate alert on all configured channels
ndelog Sentinel monitors SSL certificates across all your domains and sends alerts to WhatsApp, Telegram, Slack, or email when expiry approaches. The free Spark plan includes monitoring for 1 SSL certificate. Watchman includes 5, Warden includes 20, Pamong includes 75.
SSL Monitoring for Freelancers Managing Client Sites
If you're a freelance developer managing 10 client sites, you have 10 SSL certificates to track. Without automation:
- Each one needs a separate calendar reminder
- Renewal notifications from registrars go to client email addresses (not yours)
- The client has no idea a certificate is about to expire — they just notice when users start calling
With ndelog:
- All 10 certificates in one dashboard
- WhatsApp alert 30 days before any expiry
- You handle renewal before the client knows it was an issue
That's the difference between "our dev is proactive" and "why is our site showing a security error?"
One More SSL Risk: Third-Party Dependencies
Your site's SSL might be fine. But if you're loading scripts, fonts, or APIs from external services with expiring certificates, your users see the same browser warning.
Proactive certificate monitoring should cover not just your domains, but any external dependencies your applications rely on. This is a more advanced use case, but worth being aware of.