Alerts

An alert tells you when your workflows behave in a way you want to know about: repeated failures, a slow run, an expensive run, or no activity at all. You set up an alert once on a workspace, choose the condition that triggers it, and pick how you want to be told.

Alert rules

An alert rule is the condition that fires the alert. Each alert has one rule, configured with its own thresholds.

The rate-based rules (failure rate, latency spike) need at least 5 runs in the window before they evaluate. No-activity is checked by a background poll rather than on each run. After an alert fires, that alert stays quiet for 1 hour so a single problem doesn't flood you.

You can scope a rule to all workflows or specific ones, and filter by level (info or error) and by trigger type.

Delivery channels

An alert can reach you three ways:

• Webhook posts a signed JSON payload to a URL you provide.
• Email sends to a list of recipients, up to 10.
• Slack posts to a channel through a connected Slack account.

Webhook payload

A webhook alert is an HTTP POST with a JSON body:

{
  "id": "evt_...",
  "type": "workflow.execution.completed",
  "timestamp": 1719907200000,
  "data": {
    "workflowId": "wf_...",
    "workflowName": "Lead scorer",
    "executionId": "exec_...",
    "status": "error",
    "level": "error",
    "trigger": "api",
    "startedAt": "2026-06-01T12:00:00.000Z",
    "endedAt": "2026-06-01T12:00:01.200Z",
    "totalDurationMs": 1200,
    "cost": { "total": 0.0042 }
  }
}

You can also include the run's finalOutput, its traceSpans (webhook only), rate-limit status, and usage data by turning those options on for the alert.

Verifying a webhook

Each delivery is signed so you can confirm it came from Sim. The signature is in the sim-signature header:

sim-signature: t=1719907200000,v1=<hex>

To verify, compute an HMAC-SHA256 over {t}.{raw_body} using your webhook secret, and compare the result to v1:

import { createHmac } from 'node:crypto'

function verify(rawBody, signatureHeader, secret) {
  const parts = Object.fromEntries(signatureHeader.split(',').map((p) => p.split('=')))
  const expected = createHmac('sha256', secret).update(`${parts.t}.${rawBody}`).digest('hex')
  return expected === parts.v1
}

Sim also sends sim-event, sim-timestamp, and an Idempotency-Key header on each delivery, so a receiver can dedupe retries.

Retries

If your endpoint does not return a 2xx, Sim retries up to 5 times with increasing delays of 5s, 15s, 60s, 3m, then 10m, each with a little jitter. After the fifth failure the delivery is marked failed.

Setting up an alert

Configure alerts in your workspace notification settings, or through the workspace notifications API:

• GET /api/workspaces/{id}/notifications lists alerts.
• POST /api/workspaces/{id}/notifications creates one.
• PUT /api/workspaces/{id}/notifications/{notificationId} updates one.
• DELETE /api/workspaces/{id}/notifications/{notificationId} removes one.
• POST /api/workspaces/{id}/notifications/{notificationId}/test sends a test.

Creating or changing an alert needs Write or Admin access to the workspace. A workspace can have up to 10 alerts of each channel type.

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