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Website checks

A website check requests a URL on a schedule and alerts when the URL stops working, or answers with a status code you don’t expect.

In Add check, choose one of these under Alert us when…, then enter the URL to monitor. If you leave out http:// or https://, https:// is added.

Alert us when… Down when
URL becomes unavailable Any of the failures listed below.
URL returns HTTP status other than The response’s status code isn’t one you list.

For URL returns HTTP status other than, fill in Expected HTTP status codes with codes or ranges, such as 200-299, 301. TunnelHQ alerts on any other code.

To add many URLs at once, use Bulk import.

With URL becomes unavailable, a check is down when:

  • There’s no answer: the connection is refused or reset, DNS fails, or nothing arrives within the request timeout.
  • The status is outside 200–299. With Follow redirects on, it’s judged after up to 10 redirects. With it off, the redirect itself is judged, so a redirect counts as down.
  • The certificate is invalid, expired, or self-signed, while SSL/TLS verification is on.
  • The response body is over 10 MB.
  • The host has no address of the chosen IP version, such as “ipv4.google.com has no IPv6 address”.
  • A redirect points to a private or reserved address.
Setting Options
Request method GET (the default), HEAD, POST, PUT, PATCH, DELETE, or OPTIONS.
Body Sent only with POST, PUT, PATCH, and DELETE. JSON (sent as application/json; must be valid JSON), Form (name=value&other=2), or XML (sent as text/xml).
Headers Name and value pairs, sent with every check.
Basic auth Basic auth username and Password. Leave both empty for none.

Headers, the body, and basic auth are shown only to people whose role can edit monitors. Everyone else sees that the check has request secrets, but not their values.

  • Follow redirects is on by default and follows up to 10 redirects.
  • SSL/TLS verification is on by default and treats an invalid, expired, or self-signed certificate as down.
  • SSL expiration alerts before the site’s certificate expires. New checks with an https:// address start at Alert 14 days before.
  • Domain expiration alerts before the domain’s registration expires. It’s off by default.

An expiring certificate or domain opens an Expiring incident that closes by itself on renewal. See SSL and domain expiration.

Check frequency, the confirmation period, and the request timeout are described in Working with checks.