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Webhook

POSTs the event as JSON to an endpoint you own. Use it to feed a SIEM, trigger automation, or bridge to a tool Willow does not support directly.

Webhooks are audience-independent: they post to the endpoints you select, never to people.

Add an endpoint​

  1. Go to Security > Alerts > Channels.
  2. Under Destinations, select Webhook.
  3. Name it (e.g. SIEM ingest) and enter the endpoint URL.
  4. Select Add, then Test to confirm it is reachable.

Then turn Webhook on for a rule delivery and select the endpoint. A delivery with Webhook enabled but no endpoint selected is rejected when you save it.

Payload​

Sent with Content-Type: application/json, timing out after 5 seconds.

{
  "timestamp": "2026-09-07T10:30:00.000Z",
  "type": "notification",
  "event_type": "skill_guard.blocked",
  "event_label": "Skill Guard · Skill blocked",
  "severity": "high",
  "title": "Skill blocked: Invoice Summarizer",
  "message": "The *Invoice Summarizer* skill was blocked before it could run.",
  "default_title": "Skill blocked: Invoice Summarizer",
  "default_message": "The *Invoice Summarizer* skill was blocked before it could run.",
  "action_url": "https://app.withwillow.ai/alerts?alert=…",
  "metadata": {
    "skill_name": "Invoice Summarizer",
    "source": "Device scan",
    "actor": "user@example.com",
    "device": "MacBook-Pro",
    "guards": "Prompt Injection Detection"
  }
}
FieldNotes
event_typeStable machine identifier. See the event list.
severitycritical, high, medium, or low, after any rule override.
title / messageThe rendered text, including any template you configured.
default_title / default_messageThe system-generated text, ignoring templates.
action_urlDeep link into the Willow dashboard, when available.
metadataEvent-specific context; the keys vary by event type.
Parse the default fields, not the templated ones

title and message change the moment an admin edits a template. Machine consumers should read default_title / default_message, or better, event_type and metadata.

Reliability​

Deliveries are best-effort and fire-and-forget: the guard decision, tool call, or scan is never blocked waiting on your endpoint.

  • Requests time out after 5 seconds — respond quickly and do your processing asynchronously.
  • Each endpoint on a delivery gets its own audit record, so a broken staging endpoint does not mark the production one failed.
  • There are no retries. Combined with the rate limit, assume you may miss events and treat the alert history as the source of truth.

Hardening​

Willow sends no authentication header, so anything you need must live in the URL or your own checks.

  • Include a secret path segment or query token, and verify it server-side.
  • Make handling idempotent — assume a delivery may arrive more than once.
  • Allow outbound egress from your Willow deployment to the endpoint host.

Troubleshooting​

Nothing arrives. Verify the URL and that it returns a 2xx. Use Test, which reports the status your endpoint returned.

Intermittent failures. Usually the 5-second timeout. Acknowledge immediately and process in the background.

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