TLS Certificate monitors
Checks the TLS/SSL certificate served by a host and warns before it expires. A lapsed certificate breaks HTTPS for every visitor, so this monitor gives you a heads-up while there's still time to renew.
Fields
| Field | Required | Description |
|---|---|---|
| Host | Yes | The hostname serving the certificate, e.g. example.com. |
| Port | No | TLS port. Defaults to 443. |
| Warn under (days) | No | Mark the monitor DEGRADED when fewer than this many days remain. Defaults to 20. |
Statuses
- UP — the certificate is valid and has more than Warn under days remaining.
- DEGRADED — the certificate is still valid but expiring soon (within the warning window).
- DOWN — the certificate is expired, not yet valid, or the TLS handshake failed.
Example
Host: example.com
Port: 443
Warn under: 20 (turns DEGRADED 20 days before expiry)
Important
Renew well before the warning window. If you use automated renewal (e.g. ACME), this monitor is a safety net that tells you when renewal silently stops working.