Certificate expiry

Hear about a TLS certificate before it expires.

Add the public HTTPS URL. SignalWatch reads the certificate on each check and sends cert.expiring when it is inside 14 days, then again inside 3 days.

No card required. 3 monitors on the free plan. The preview shows certificate days remaining when the fetch succeeds.

What you receive

The event is cert.expiring. The payload includes cert_days_left, cert_not_after, and cert_issuer, plus the URL and HTTP status. Email, Slack, and Discord say how many days are left. You are not mailed on every poll.

{
  "event": "cert.expiring",
  "url": "https://example.com/",
  "status_code": 200,
  "cert_days_left": 12,
  "cert_not_after": "2026-10-15T00:00:00+00:00",
  "cert_issuer": "Example CA"
}

That JSON is a presentation example, using the same fields a real alert carries.

It stays on the same monitor

You do not create a second check for the certificate. The page text, downtime, recovery, and TLS expiry share one URL and one schedule: 15 minutes on Free, 5 minutes on Pro, 2 minutes on Business. A content change still sends content.changed with a diff. A failed fetch still sends check.down, and the next success sends check.up.

If you only wanted the certificate and the page text is noisy, raise the minimum-change percentage or set an ignore regex. Certificate alerts are not filtered by that percentage.

What it will not claim

It does not renew the certificate for you.
It does not inspect certificates on private hosts, localhost, or addresses SignalWatch refuses as non-public.
It does not replace a certificate authority’s renewal emails. It is a second notice on the public URL you already watch.
HTTP URLs have no TLS certificate to report.

Confirm delivery first

After the monitor exists, use Send test alert in the dashboard. The test event is test, not cert.expiring, and it proves the email or webhook path. Signed webhook details are in the webhook guide. Plan limits are on pricing.

FAQ

When does SignalWatch alert on a certificate?

Once when the certificate is inside 14 days of expiry, and again when it is inside 3 days. It does not send cert.expiring on every check.

Do I need a separate monitor for TLS?

No. Every HTTPS monitor checks the certificate on the same schedule as the page. You still get content changes, downtime, and recovery for that URL.

Will this see certificates on private hosts?

No. SignalWatch only fetches public HTTP(S) URLs. Private network addresses are rejected. It also does not replace your certificate authority’s own renewal dashboard.