SSL certificate monitoring with expiry alerts you cannot miss

Why automated renewal is not enough

ACME clients renew certificates automatically until something quietly stops working: an HTTP-01 challenge blocked by a redirect, a DNS-01 record removed during a migration, a cron job on a decommissioned host, or a rate limit hit during a bulk renewal. The renewal fails silently and the first signal is an outage. Independent expiry monitoring is the control that catches it.

• Certificate lifetimes are shrinking industry-wide, so renewal now happens far more often and has more chances to fail.
• A certificate that renews on the origin but is not reloaded by the web server still serves the old one.
• Load balancers and CDNs often hold their own copy of the certificate that must be updated separately.

What ServerInspector checks

For every HTTPS target, the monitor completes a real TLS handshake and inspects the certificate the server actually presents — not a cached record from a registry. That means the data reflects what your visitors see.

• Expiry date and remaining days, shown as an exact date in the dashboard.
• Issuing certificate authority so you can spot an unexpected issuer change.
• Handshake and validation failures, including hostname mismatch and untrusted chains.
• Historical status so you can see when a certificate was replaced.

Reminders that reach the right person

Certificate ownership often sits with a different person than uptime on-call. Each monitor can send expiry reminders to its own email address, on the thresholds you choose, and you can send a test message to confirm delivery before it matters.

• Default reminder thresholds of 30, 14, 7 and 1 day, editable per monitor or domain.
• A weekly digest listing every certificate and domain sorted by expiry date.
• Slack, Discord, Telegram and webhook delivery alongside email.

Diagnose the failure, not just the symptom

When a certificate check fails, the alert carries the underlying reason so the fix is obvious: expired leaf, incomplete chain, mismatched hostname, or a protocol negotiation error. Pair it with uptime monitoring so you can tell a TLS problem apart from an application outage.