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When you configure a webhook, Zenzap sends HTTP POST requests to your URL when events occur. This page documents the payload structure for each event type.

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Event Envelope

All webhook events share the same envelope structure: 
{
  "id": "evt_550e8400-e29b-41d4-a716-446655440099",
  "type": "message.created",
  "eventVersion": 1,
  "timestamp": 1699564800000,
  "data": { ... }
}
FieldTypeDescription
idstringUnique event ID (use for deduplication)
typestringEvent type (see below)
eventVersionintegerSchema version (currently 1)
timestampintegerUnix timestamp in milliseconds
dataobjectEvent-specific payload

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HTTP Headers

Each webhook delivery includes these headers:
HeaderDescription
X-Zenzap-EventEvent type (e.g., message.created)
X-Zenzap-SignatureHMAC-SHA256 signature for verification
X-Zenzap-TimestampUnix timestamp (milliseconds) when sent
X-Zenzap-Delivery-IdUnique delivery ID (for deduplication)

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Signature Verification

When a secret is configured, verify webhooks by calculating: 
import hmac
import hashlib

def verify_webhook(payload: bytes, signature: str, timestamp: str, secret: str) -> bool:
    expected = hmac.new(
        secret.encode(),
        f"{timestamp}.{payload.decode()}".encode(),
        hashlib.sha256
    ).hexdigest()
    return hmac.compare_digest(expected, signature)

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Message Events

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message.created

Sent when a new message is posted in a topic where your bot is a member. 
{
  "id": "evt_550e8400-e29b-41d4-a716-446655440099",
  "type": "message.created",
  "eventVersion": 1,
  "timestamp": 1699564800000,
  "data": {
    "message": {
      "id": "660e8400-e29b-41d4-a716-446655440001",
      "topicId": "550e8400-e29b-41d4-a716-446655440000",
      "senderId": "u@550e8400-e29b-41d4-a716-446655440001",
      "senderName": "Alice Johnson",
      "senderType": "user",
      "type": "text",
      "text": "Hello team!",
      "createdAt": 1699564800000
    }
  }
}

​
message.updated

Sent when a message is edited or when voice message transcription completes. 
{
  "id": "evt_550e8400-e29b-41d4-a716-446655440099",
  "type": "message.updated",
  "eventVersion": 1,
  "timestamp": 1699564850000,
  "data": {
    "message": {
      "id": "660e8400-e29b-41d4-a716-446655440001",
      "topicId": "550e8400-e29b-41d4-a716-446655440000",
      "senderId": "u@550e8400-e29b-41d4-a716-446655440001",
      "senderName": "Alice Johnson",
      "senderType": "user",
      "type": "text",
      "text": "Hello team! (edited)",
      "createdAt": 1699564800000,
      "updatedAt": 1699564850000
    }
  }
}

​
message.deleted

Sent when a message is deleted. 
{
  "id": "evt_550e8400-e29b-41d4-a716-446655440099",
  "type": "message.deleted",
  "eventVersion": 1,
  "timestamp": 1699564900000,
  "data": {
    "messageId": "660e8400-e29b-41d4-a716-446655440001",
    "topicId": "550e8400-e29b-41d4-a716-446655440000",
    "deletedBy": "u@550e8400-e29b-41d4-a716-446655440001"
  }
}

​
Message Object

The message object in message events contains:
FieldTypeDescription
idstringMessage UUID
topicIdstringTopic UUID
senderIdstringSender ID (format: u@{uuid} for users, b@{uuid} for bots)
senderNamestringSender’s display name
senderTypestringuser, bot, or system
typestringMessage type (see below)
textstringMessage text (may be empty for non-text types)
createdAtintegerCreation timestamp (ms)
updatedAtintegerLast update timestamp (ms)
parentIdstringReplied-to message ID
attachmentsarrayFile attachments
mentionsarrayUser mentions
locationobjectLocation data (for location messages)
taskobjectTask data (for task messages)
contactobjectContact data (for contact messages)

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Message Types

TypeDescriptionAdditional Fields
textRegular text messagetext
imageImage attachmentattachments[]
fileFile attachmentattachments[]
videoVideo attachmentattachments[]
audioVoice messageattachments[] (with transcription)
locationShared locationlocation
taskTask snapshottask
contactShared contactcontact

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Attachments

File attachments include a signed download URL: 
{
  "attachments": [
    {
      "id": "att_550e8400-e29b-41d4-a716-446655440088",
      "type": "image",
      "name": "screenshot.png",
      "url": "https://storage.zenzap.co/attachments/...?token=...&expires=..."
    }
  ]
}
Attachment URLs expire after 60 minutes. Download files promptly after receiving the webhook.

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Voice Message Transcription

Voice messages (audio attachments) are automatically transcribed. The flow is:
  1. message.created arrives with transcription.status: "Pending"
  2. message.updated arrives when transcription completes
{
  "type": "message.updated",
  "data": {
    "message": {
      "type": "audio",
      "attachments": [
        {
          "id": "att_...",
          "type": "audio",
          "name": "voice-note.mp3",
          "url": "https://storage.zenzap.co/...",
          "transcription": {
            "status": "Done",
            "text": "Hey team, just a quick update on the project..."
          }
        }
      ]
    }
  }
}
Transcription Status Values:
StatusDescription
PendingQueued for transcription
StartedTranscription in progress
DoneComplete - text field populated
FailedTranscription failed

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Reply Messages

Messages that reply to other messages include: 
{
  "message": {
    "id": "msg_new",
    "text": "I agree!",
    "parentId": "msg_original"
  }
}

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Location Messages

{
  "message": {
    "type": "location",
    "text": "",
    "location": {
      "latitude": "37.7749",
      "longitude": "-122.4194",
      "name": "San Francisco Office",
      "address": "123 Market St, San Francisco, CA"
    }
  }
}
address is optional and is included only when available.

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Task Messages

Task snapshots are sent when tasks are created, updated, or their status changes: 
{
  "message": {
    "type": "task",
    "text": "",
    "task": {
      "id": "task_...",
      "action": "Added",
      "title": "Review documentation",
      "text": "Please review the API docs by Friday",
      "status": "Open",
      "assignee": "u@550e8400-e29b-41d4-a716-446655440001",
      "dueDate": 1699651200000,
      "isDueDateTimeSelected": true,
      "parentId": null,
      "subItemsCount": 0
    }
  }
}
Task Actions:
ActionDescription
AddedTask created
UpdatedTask details changed
DeletedTask removed
MarkedAsDoneTask completed
MarkedAsOpenedTask reopened
RepliedComment added to task

​
Contact Messages

{
  "message": {
    "type": "contact",
    "text": "",
    "contact": {
      "name": "John Doe",
      "phoneNumbers": ["+1234567890"],
      "emails": ["john@example.com"],
      "role": "Engineer",
      "location": "San Francisco",
      "linkedIn": "https://linkedin.com/in/johndoe",
      "profileId": "u@550e8400-e29b-41d4-a716-446655440001"
    }
  }
}

​
Reaction Events

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reaction.added

{
  "id": "evt_...",
  "type": "reaction.added",
  "eventVersion": 1,
  "timestamp": 1699564800000,
  "data": {
    "messageId": "660e8400-e29b-41d4-a716-446655440001",
    "topicId": "550e8400-e29b-41d4-a716-446655440000",
    "emoji": "👍",
    "userId": "u@550e8400-e29b-41d4-a716-446655440001",
    "userName": "Alice Johnson"
  }
}

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reaction.removed

Same structure as reaction.added.

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Member Events

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member.added

{
  "id": "evt_...",
  "type": "member.added",
  "eventVersion": 1,
  "timestamp": 1699564800000,
  "data": {
    "topicId": "550e8400-e29b-41d4-a716-446655440000",
    "memberId": "u@550e8400-e29b-41d4-a716-446655440003",
    "memberName": "Carol Williams",
    "addedBy": "u@550e8400-e29b-41d4-a716-446655440001"
  }
}

​
member.removed

{
  "id": "evt_...",
  "type": "member.removed",
  "eventVersion": 1,
  "timestamp": 1699564800000,
  "data": {
    "topicId": "550e8400-e29b-41d4-a716-446655440000",
    "memberId": "u@550e8400-e29b-41d4-a716-446655440003",
    "memberName": "Carol Williams",
    "removedBy": "u@550e8400-e29b-41d4-a716-446655440001"
  }
}

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Topic Events

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topic.updated

Sent when a topic’s name or description is changed. 
{
  "id": "evt_...",
  "type": "topic.updated",
  "eventVersion": 1,
  "timestamp": 1699564800000,
  "data": {
    "topicId": "550e8400-e29b-41d4-a716-446655440000",
    "name": "Project Updates - Q4",
    "updatedBy": "u@550e8400-e29b-41d4-a716-446655440001"
  }
}
Only changed fields are included in the payload. If only the description was updated, name would be absent.

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Retry & Auto-Pause Behavior

  • Webhooks are retried up to 3 times with exponential backoff on failure
  • After 10 consecutive failures, the webhook is automatically paused
  • Re-enable a paused webhook via the Update webhook configuration endpoint