---
title: SSL certificate monitors
description: Get warned before an SSL/TLS certificate expires.
category: monitors
updated: 2026-07-15
tags: [ssl, tls, certificate, expiry]
---

An SSL monitor connects to your service, inspects its certificate, and warns you
well before it expires. An expired certificate makes browsers show a scary warning
and can take a site down instantly — this monitor makes sure that never surprises
you.

![An SSL monitor's detail panel, showing the certificate is valid with 22 days remaining before expiry, alongside its check interval and alert thresholds](/img/docs/app-monitor-ssl.png)
*The countdown to expiry is shown on the monitor itself, so you see it without
opening anything.*

## Setting it up

- **Target** — the domain to check, e.g. `example.com`. It checks port 443 by
  default; add `:port` if your TLS service runs elsewhere.

## What it tracks

- **Days until expiry**, shown right on the monitor.
- **Issuer** and validity dates.
- Whether the certificate is already **expired** (which reads as down).

## Expiry alerts

You choose two thresholds per monitor:

- **Warning** — how many days before expiry to send a first heads-up (default: 14
  days).
- **Critical** — a more urgent reminder as the deadline approaches (default: 7 days).

Both are adjustable from 1 to 365 days, and the critical threshold must be sooner
than the warning one.

## Good to know

- An SSL monitor reports on the certificate even if the chain is self-signed or
  expired — its job is to tell you the state of the cert, not to block on it.
- It's independent of your [HTTP monitor](/docs/monitors/http): run both so you're
  covered for "site is down" *and* "cert is about to lapse".

## Get started

- [Create an SSL monitor](/docs/getting-started/quickstart)
- [Set notification channels](/docs/alerts/notification-channels)

## Related

- [Domain expiry monitors](/docs/monitors/domain)
- [HTTP / website monitors](/docs/monitors/http)