Webhooks

A webhook destination is a plain HTTP POST — any receiver that accepts the payload works.

A webhook destination is an HTTP POST with a Slack-style JSON body. Any endpoint that accepts that shape works — a Slack incoming webhook, a relay, or your own service. To send a different shape, attach a transformation.

The built-in payload

When an incident is confirmed, when a reminder about it comes due, and when it closes, Uptimer POSTs:

{
  "attachments": [
    {
      "author_name": "Uptimer",
      "title": "Checkout API is down",
      "color": "#d50201",
      "text": "Failing from 2 of 3 locations — de, fr\n`dial tcp 104.20.23.154:9: i/o timeout`\nDown for 2m before we alerted.\n<https://uptimer.example.com/ui/workspace/{workspace}/monitoring/subject/{subject}|View timeline>",
      "footer": "Uptimer",
      "timestamp": 1786642711
    }
  ]
}

The title is the monitor name plus its state, and the colour follows it:

A four-hour reminder about a problem nobody has answered is the same payload as the problem alert, with the elapsed time in its text. There is no reminder-specific type, title or colour to branch on: a consumer that already handles the confirmed-problem message handles reminders without a change.

The text is plain text with Slack’s <url|label> link syntax, so a non-Slack consumer should expect that markup rather than HTML or Markdown.

The link points at the subject timeline (/ui/workspace/{workspace}/monitoring/subject/{subject}). The subject id is an opaque id, not a database number. A monitor that somehow has no subject yet keeps the older /rule/{uid}/history link so an alert never links nowhere. Its host comes from general.site_url; when that is unset the URL reads SITE_URL_NOT_CONFIGURED/ui/… and the alert is still sent.

Sending a different shape

Attach a transformation to the destination and it receives that template rendered instead — a PagerDuty event, your own JSON, a line of text. The content type follows the template: application/json when it reads as JSON, text/plain otherwise. A destination with no transformation gets the body above.

What this release does not do

New in 1.8.0: a workspace has as many destinations as it needs, each subject chooses its own (Alert delivery), payloads are templatable, and every attempt is recorded for 30 days (Delivery log).

Still out of scope: no retries (one attempt, recorded either way), no custom headers, and no other channels — no email, no SMS, no PagerDuty integration beyond posting the shape its events API accepts. Routing is per subject and per alert kind; there is no per-rule switch.