Slack fixture

`event_callback (app_mention)`

Slack delivers all Events API messages as `event_callback`, with the actual event nested under `event`. This example is an app_mention — your bot was @-mentioned in a channel.

When does it fire?

A user mentions your Slack app in a channel where the app is installed. Slack also expects a 200 OK within 3 seconds — ack first, process later.

Request headers

Content-Type: application/json
X-Slack-Request-Timestamp: 1715600000
X-Slack-Signature: v0=a2114d57b48eac39b9ad189dd8316235a7b4a8d21a10bd27519666489c69b503

Payload

{
  "token": "verification-token-deprecated",
  "team_id": "T01234567",
  "api_app_id": "A01234567",
  "type": "event_callback",
  "event_id": "Ev08MFMKH6",
  "event_time": 1715600000,
  "event": {
    "type": "app_mention",
    "user": "U02345678",
    "text": "<@U03456789> deploy staging please",
    "ts": "1715600000.001500",
    "channel": "C04567890",
    "event_ts": "1715600000.001500"
  }
}

Key fields

event_id
Unique event ID. Use as dedup key.
event.type
Nested event type — app_mention, message, reaction_added, etc.
event.channel
Channel ID to respond into via chat.postMessage.
X-Slack-Signature
Verify with HMAC-SHA256 over `v0:{timestamp}:{body}` and your signing secret.

Test it with cURL

Replace your-endpoint with your HookSense endpoint slug — or any URL you want to test against.

curl -X POST https://hooksense.com/w/your-endpoint \
  -H "Content-Type: application/json" \
  -H "X-Slack-Request-Timestamp: 1715600000" \
  -H "X-Slack-Signature: v0=a2114d57b48eac39b9ad189dd8316235a7b4a8d21a10bd27519666489c69b503" \
  -d '{
  "token": "verification-token-deprecated",
  "team_id": "T01234567",
  "api_app_id": "A01234567",
  "type": "event_callback",
  "event_id": "Ev08MFMKH6",
  "event_time": 1715600000,
  "event": {
    "type": "app_mention",
    "user": "U02345678",
    "text": "<@U03456789> deploy staging please",
    "ts": "1715600000.001500",
    "channel": "C04567890",
    "event_ts": "1715600000.001500"
  }
}'

Capture this in HookSense

Fire the cURL above at your HookSense endpoint and inspect the request in real time — with headers, body, signature verification, and replay.

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More Slack fixtures

Slack integration guide →