Free SSL Certificate Monitoring
upsonar.io monitors your SSL/TLS certificates and alerts you before they expire. Validates certificate chains, checks TLS protocol versions, and verifies issuer trust — automatically, every day.
Alerts at 30, 14, 7 days before expiry · Chain validation · Free plan available
What is SSL certificate monitoring?
SSL certificate monitoring is the continuous automated checking of a website's TLS certificate to verify it is valid, correctly installed, and not approaching expiration. A monitoring service fetches the certificate from the domain on a regular schedule (typically daily), parses the expiry date and issuer, validates the full certificate chain against trusted root certificate authorities, verifies that the certificate covers the correct hostnames (SAN/wildcard match), and checks supported TLS protocol versions. When a check fails or the expiry date approaches a configured threshold, the monitor sends an alert — usually via email, Telegram, Slack, or webhook. Independent SSL monitoring is the only reliable safety net against silent auto-renewal failures.
Why SSL Monitoring Matters
Browser Warnings
Expired SSL = full-page security warning. Most visitors leave immediately. Your site is effectively offline.
Silent Renewal Failures
Auto-renewal fails silently due to DNS changes, firewall rules, or expired payment methods. Independent monitoring catches this.
30-Day Early Warning
Get alerts at 30, 14, and 7 days before expiry. Plenty of time to renew or fix auto-renewal issues.
How SSL Monitoring Works
The monitor opens a TLS connection. Every check cycle, Upsonar opens a fresh TLS 1.2 or 1.3 connection to your domain on port 443 from each of 9 global regions. The server's certificate is captured during the TLS handshake along with any intermediate certificates the server sends. No browser is involved — the check is a pure protocol-level handshake that takes under a second.
The certificate is parsed and validated. Upsonar extracts the notBefore and notAfter dates, the issuer (Common Name of the issuing CA), the subject alternative names (SANs) to verify your hostname is covered, and the signature algorithm. The full certificate chain is then walked upward: leaf → intermediate(s) → root, with every signature verified against the NSS trust store (the same root CA list Chrome and Firefox ship with). Incomplete chains — a very common misconfiguration that works in Chrome but fails in mobile Safari and curl — are detected here.
Alerts fire at 30, 14, and 7 days before expiry. When the notAfter date crosses any alert threshold, Upsonar creates an incident and sends a notification through every configured channel (email, Telegram, Slack, webhook). Each alert includes the certificate expiry date, days remaining, issuer, and a direct link to the incident with the full diagnostic data. Multi-threshold alerting is critical because troubleshooting a broken ACME auto-renewal can take days — the first 30-day alert gives teams time to fix the underlying problem without an emergency page.
What We Check
Check Your SSL Certificate Now
Free instant SSL check — validity, expiry, chain, TLS version. No signup required.
Frequently Asked Questions
Never Miss an SSL Expiry Again
Free plan includes SSL monitoring for 3 websites with email and Telegram alerts. No credit card required.
Set up in 30 seconds · Free forever
Last updated: April 2026