Webhooks

Webhooks allow you to receive real-time notifications when events occur within Asteroid. Set up HTTP endpoints to automatically receive event data as it happens.

This documentation covers Webhook V2. If you’re using V1, see the Migration Guide below.

Overview

Real-time Notifications

Get instant updates for all execution lifecycle events

Secure Delivery

Webhooks are signed with cryptographic signatures for verification

Reliable Delivery

Automatic retries ensure your webhooks are delivered

Event-Specific Payloads

Structured payloads with execution context and event-specific data

Configuration

Setting Up Your Webhook

Create Webhook V2 Integration in Platform

In the platform, go to Integrations → Add Integration → select Webhook, then supply the webhook details:

URL: The endpoint that will receive execution events
Headers: Any custom headers required by your endpoint (e.g., authentication)

Webhooks use a standardized payload structure and do not require custom body templates.

Attach Webhook to Agents

After creating the integration, attach the webhook to individual agents. When those agents run and emit execution events, your webhook will be invoked automatically.

Verify Webhook Signature

All webhooks include a cryptographic signature for security verification (see Security section).

V2 Payload Structure

Every webhook request contains a standardized V2 payload structure:

{
  "type": "execution",
  "event_id": "8106b11d-564d-4192-a03a-5f81418c70d5",
  "timestamp": "2024-01-15T10:30:00Z",
  "info": {
    "event": "EXECUTION_COMPLETED",
    "execution_id": "5f813ea4-6713-4879-b1f5-c5e9f7e8040d",
    "execution_url": "https://platform.asteroid.ai/executions/5f813ea4-6713-4879-b1f5-c5e9f7e8040d",
    "agent_id": "4d407b97-cbde-4e0b-8d7f-a0e8d7ba6a06",
    "agent_name": "Data Extraction Agent",
    "payload": {
      "result": { /* execution result data */ },
      "reasoning": "Task completed successfully",
      "outcome": "Success"
    }
  }
}

Top-Level Fields

type

string

required

The category of the notification. Currently only "execution" is supported.

event_id

string

required

Unique identifier for this notification event. Use this for idempotency.Example: 8106b11d-564d-4192-a03a-5f81418c70d5

timestamp

string

required

ISO 8601 timestamp when the event occurred.Example: 2024-01-15T10:30:00Z

info

object

required

Type specific event information. See Execution Info below.

Execution Info Structure

When the type is Execution, the info object contains execution-specific details:

info.event

string

required

The specific execution event type. One of:

EXECUTION_STARTED
EXECUTION_COMPLETED
EXECUTION_FAILED
EXECUTION_CANCELLED
EXECUTION_PAUSED
EXECUTION_RESUMED
EXECUTION_AWAITING_CONFIRMATION

info.execution_id

string

required

Unique identifier for the execution.Example: 5f813ea4-6713-4879-b1f5-c5e9f7e8040d

info.execution_url

string

required

URL to view the execution in the Asteroid platform.Example: https://platform.asteroid.ai/executions/5f813ea4-6713-4879-b1f5-c5e9f7e8040d

info.agent_id

string

required

Identifier of the agent that is being run.

info.agent_name

string

required

Human-readable name of the agent that is being run.

info.payload

object

required

Event-specific payload data. The structure depends on the event field. See Execution Events below.

Execution Events

Each execution event type has a specific payload structure:

EXECUTION_STARTED

Sent when an execution begins. Payload: Empty object {}

{
  "type": "execution",
  "event_id": "evt_001",
  "timestamp": "2024-01-15T10:30:00Z",
  "info": {
    "event": "EXECUTION_STARTED",
    "execution_id": "4d407b97-cbde-4e0b-8d7f-a0e8d7ba6a06",
    "execution_url": "https://platform.asteroid.ai/executions/4d407b97-cbde-4e0b-8d7f-a0e8d7ba6a06",
    "agent_id": "4d407b97-cbde-4e0b-8d7f-a0e8d7ba6a06",
    "agent_name": "Data Extraction Agent",
    "payload": {}
  }
}

EXECUTION_COMPLETED

Sent when an execution completes successfully. Payload:

result

object

required

Execution result data returned by the agent.

reasoning

string

required

Reasoning for the execution outcome.

outcome

string

required

Execution outcome description.

{
  "type": "execution",
  "event_id": "evt_002",
  "timestamp": "2024-01-15T10:35:00Z",
  "info": {
    "event": "EXECUTION_COMPLETED",
    "execution_id": "4d407b97-cbde-4e0b-8d7f-a0e8d7ba6a06",
    "execution_url": "https://platform.asteroid.ai/executions/4d407b97-cbde-4e0b-8d7f-a0e8d7ba6a06",
    "agent_id": "4d407b97-cbde-4e0b-8d7f-a0e8d7ba6a06",
    "agent_name": "Data Extraction Agent",
    "payload": {
      "result": {
        "data": "extracted data",
        "status": "success"
      },
      "reasoning": "Successfully extracted all required data",
      "outcome": "Task completed successfully"
    }
  }
}

EXECUTION_FAILED

Sent when an execution fails. Payload:

reason

string

required

Reason for the failure.

{
  "type": "execution",
  "event_id": "evt_003",
  "timestamp": "2024-01-15T10:35:00Z",
  "info": {
    "event": "EXECUTION_FAILED",
    "execution_id": "4d407b97-cbde-4e0b-8d7f-a0e8d7ba6a06",
    "execution_url": "https://platform.asteroid.ai/executions/4d407b97-cbde-4e0b-8d7f-a0e8d7ba6a06",
    "agent_id": "4d407b97-cbde-4e0b-8d7f-a0e8d7ba6a06",
    "agent_name": "Data Extraction Agent",
    "payload": {
      "reason": "Unable to access target website - connection timeout"
    }
  }
}

EXECUTION_CANCELLED

Sent when an execution is cancelled. Payload:

reason

string

required

Reason for cancellation.

cancelled_by

string

required

Who cancelled the execution (e.g., “user”, “system”, “admin”).

{
  "type": "execution",
  "event_id": "evt_004",
  "timestamp": "2024-01-15T10:32:00Z",
  "info": {
    "event": "EXECUTION_CANCELLED",
    "execution_id": "4d407b97-cbde-4e0b-8d7f-a0e8d7ba6a06",
    "execution_url": "https://platform.asteroid.ai/executions/4d407b97-cbde-4e0b-8d7f-a0e8d7ba6a06",
    "agent_id": "4d407b97-cbde-4e0b-8d7f-a0e8d7ba6a06",
    "agent_name": "Data Extraction Agent",
    "payload": {
      "reason": "User requested cancellation",
      "cancelled_by": "user"
    }
  }
}

EXECUTION_PAUSED

Sent when an execution is paused. Payload:

reason

string

required

Reason for the pause.

For user pauses: "paused by user"
For agent pauses: the query/message sent via send_user_message

paused_by

string

required

Who paused the execution (e.g., “user”, “agent”, “system”).

{
  "type": "execution",
  "event_id": "evt_005",
  "timestamp": "2024-01-15T10:31:00Z",
  "info": {
    "event": "EXECUTION_PAUSED",
    "execution_id": "4d407b97-cbde-4e0b-8d7f-a0e8d7ba6a06",
    "execution_url": "https://platform.asteroid.ai/executions/4d407b97-cbde-4e0b-8d7f-a0e8d7ba6a06",
    "agent_id": "4d407b97-cbde-4e0b-8d7f-a0e8d7ba6a06",
    "agent_name": "Data Extraction Agent",
    "payload": {
      "reason": "Need user input: Which account should I use?",
      "paused_by": "agent"
    }
  }
}

EXECUTION_RESUMED

Sent when an execution resumes after being paused. Payload:

reason

string

required

Reason for the resumption.

{
  "type": "execution",
  "event_id": "evt_006",
  "timestamp": "2024-01-15T10:33:00Z",
  "info": {
    "event": "EXECUTION_RESUMED",
    "execution_id": "4d407b97-cbde-4e0b-8d7f-a0e8d7ba6a06",
    "execution_url": "https://platform.asteroid.ai/executions/4d407b97-cbde-4e0b-8d7f-a0e8d7ba6a06",
    "agent_id": "4d407b97-cbde-4e0b-8d7f-a0e8d7ba6a06",
    "agent_name": "Data Extraction Agent",
    "payload": {
      "reason": "User provided input"
    }
  }
}

EXECUTION_AWAITING_CONFIRMATION

Sent when an execution requires user confirmation. Payload:

reason

string

required

Reason why confirmation is needed.

{
  "type": "execution",
  "event_id": "evt_007",
  "timestamp": "2024-01-15T10:34:00Z",
  "info": {
    "event": "EXECUTION_AWAITING_CONFIRMATION",
    "execution_id": "4d407b97-cbde-4e0b-8d7f-a0e8d7ba6a06",
    "execution_url": "https://platform.asteroid.ai/executions/4d407b97-cbde-4e0b-8d7f-a0e8d7ba6a06",
    "agent_id": "4d407b97-cbde-4e0b-8d7f-a0e8d7ba6a06",
    "agent_name": "Data Extraction Agent",
    "payload": {
      "reason": "About to submit payment form - please confirm"
    }
  }
}

Security & Signature Verification

All webhooks are signed using SHA256 hashing with RSA-PKCS1v15 signing and Base64 encoding for maximum security.

Signature Header

The webhook signature is included in the X-Asteroid-Signature header:

X-Asteroid-Signature: <signature>

Always verify the webhook signature to ensure the request is authentic and hasn’t been tampered with.

Public Key for Verification

Use this Base64-encoded public key to verify webhook signatures:

LS0tLS1CRUdJTiBQVUJMSUMgS0VZLS0tLS0KTUlJQklqQU5CZ2txaGtpRzl3MEJBUUVGQUFPQ0FROEFNSUlCQ2dLQ0FRRUF0SkZ6aXdXUjROUVJzTnpqZw==

JavaScript Implementation

Here’s a complete example of verifying webhook signatures in JavaScript:

const crypto = require('crypto');

function verifyWebhook(body, signature, publicKeyBase64) {
  // Step 1: Create SHA256 verifier
  const verifier = crypto.createVerify('SHA256');

  // Step 2: Update verifier with the request body
  verifier.update(body);

  // Step 3: Convert Base64 public key to buffer
  const publicKey = Buffer.from(publicKeyBase64, 'base64');

  // Step 4: Verify the signature
  const isValid = verifier.verify(publicKey, signature, 'base64');

  return isValid;
}

// Express.js example
app.post('/webhook', express.raw({ type: 'application/json' }), (req, res) => {
  const signature = req.headers['x-asteroid-signature'];
  const isValid = verifyWebhook(req.body, signature, PUBLIC_KEY);

  if (!isValid) {
    return res.status(401).json({ error: 'Invalid signature' });
  }

  // Parse and process the webhook
  const event = JSON.parse(req.body.toString());

  switch (event.info.event) {
    case 'EXECUTION_STARTED':
      console.log('Execution started:', event.info.execution_id);
      break;
    case 'EXECUTION_COMPLETED':
      console.log('Execution completed:', event.info.payload.result);
      break;
    case 'EXECUTION_FAILED':
      console.log('Execution failed:', event.info.payload.reason);
      break;
    // Handle other events...
  }

  res.status(200).json({ received: true });
});

Migrating from V1 to V2

If you’re currently using Webhook V1, follow this guide to migrate to V2.

What Changed

V2 introduces a more structured payload format with better support for execution lifecycle events: V1 Payload:

{
  "type": "<event_type>",
  "timestamp": "<timestamp>",
  "payload": "<event_payload>"
}

V2 Payload:

{
  "type": "execution",
  "event_id": "evt_abc123",
  "timestamp": "2024-01-15T10:30:00Z",
  "info": {
    "event": "EXECUTION_COMPLETED",
    "execution_id": "4d407b97-cbde-4e0b-8d7f-a0e8d7ba6a06",
    "execution_url": "https://platform.asteroid.ai/executions/4d407b97-cbde-4e0b-8d7f-a0e8d7ba6a06",
    "agent_id": "4d407b97-cbde-4e0b-8d7f-a0e8d7ba6a06",
    "agent_name": "Data Extraction Agent",
    "payload": { /* event-specific data */ }
  }
}

Migration Steps

Update Your Endpoint Code

Modify your webhook handler to parse the new V2 structure:

app.post('/webhook', (req, res) => {
  const { type, timestamp, payload } = req.body;

  console.log(`Event: ${type} at ${timestamp}`);
  console.log('Payload:', payload);

  res.status(200).json({ received: true });
});

Update Integration in Platform

In the Asteroid platform:

Go to Integrations → find your webhook integration
Edit the integration and change the version from V1 to V2
Remove any custom body templates (V2 uses standardized payloads)
Save the changes

Once you switch to V2, your endpoint will immediately start receiving V2-formatted payloads. Ensure your code is updated first!

Test Your Integration

Trigger a test execution to verify your endpoint correctly handles V2 payloads:

Run an agent with the V2 webhook attached
Verify you receive all execution events
Check that you can parse and handle each event type
Confirm signature verification still works

Update Idempotency Logic (Recommended)

V2 includes an event_id field for better idempotency handling:

const processedEvents = new Set();

app.post('/webhook', (req, res) => {
  const { event_id } = req.body;

  // Use event_id instead of timestamp-based deduplication
  if (processedEvents.has(event_id)) {
    return res.status(200).json({ message: 'Already processed' });
  }
  // Process the event...

  processedEvents.add(event_id);
});

Best Practices

Implement Proper Error Handling

Always return appropriate HTTP status codes:

200 - Successfully processed
400 - Bad request/invalid payload
401 - Unauthorized/invalid signature
500 - Server error

Handle Duplicate Events with event_id

Use the event_id field to detect and handle duplicate webhook deliveries:

const processedEvents = new Set();

app.post('/webhook', (req, res) => {
  const { event_id } = req.body;

  if (processedEvents.has(event_id)) {
    return res.status(200).json({ message: 'Already processed' });
  }

  processedEvents.add(event_id);
  // Process the event...
});

Implement Timeout Protection

Respond to webhooks within 30 seconds to avoid timeouts and retries:

app.post('/webhook', (req, res) => {
  // Acknowledge receipt immediately
  res.status(200).json({ received: true });

  // Process asynchronously
  setImmediate(() => {
    processWebhookEvent(req.body);
  });
});

Log Execution Context

Take advantage of the rich execution context in V2:

app.post('/webhook', (req, res) => {
  const { event_id, timestamp, info } = req.body;

  console.log({
    eventId: event_id,
    timestamp: timestamp,
    executionId: info.execution_id,
    executionUrl: info.execution_url,
    agentId: info.agent_id,
    agentName: info.agent_name,
    event: info.event
  });

  // This makes debugging much easier!
});

Testing Your Webhooks

Use webhook.site to test your webhook integration during development. It provides a temporary URL that captures and displays all incoming webhook requests.

Test Payload Example

Here’s a complete V2 test payload you can use:

{
  "type": "execution",
  "event_id": "evt_test_123",
  "timestamp": "2024-01-15T10:30:00Z",
  "info": {
    "event": "EXECUTION_COMPLETED",
    "execution_id": "4d407b97-cbde-4e0b-8d7f-a0e8d7ba6a06",
    "execution_url": "https://platform.asteroid.ai/executions/4d407b97-cbde-4e0b-8d7f-a0e8d7ba6a06",
    "agent_id": "4d407b97-cbde-4e0b-8d7f-a0e8d7ba6a06",
    "agent_name": "Data Extraction Agent",
    "payload": {
      "result": {
        "status": "success",
        "data": {
          "items_processed": 42,
          "completion_time": "5.2s"
        }
      },
      "reasoning": "Successfully processed all items in the queue",
      "outcome": "Task completed successfully"
    }
  }
}

Troubleshooting

Webhook Not Receiving Events

Verify your endpoint URL is accessible from the internet
Check that your server is running and responding to POST requests
Ensure your firewall allows incoming connections

Signature Verification Failing

Confirm you’re using the correct public key
Verify you’re hashing the raw request body (not parsed JSON)
Check that you’re using Base64 decoding for both the key and signature

Receiving Duplicate Events

Implement idempotency using the event_id field
Return 200 status code for successfully processed events
Avoid returning error codes for already-processed events

Get Started

Astro

Fundamentals

SDKs

What's New

Support & Security

Overview

Real-time Notifications

Secure Delivery

Reliable Delivery

Event-Specific Payloads

Configuration

Setting Up Your Webhook

V2 Payload Structure

Top-Level Fields

Execution Info Structure

Execution Events

EXECUTION_STARTED

EXECUTION_COMPLETED

EXECUTION_FAILED

EXECUTION_CANCELLED

EXECUTION_PAUSED

EXECUTION_RESUMED

EXECUTION_AWAITING_CONFIRMATION

Security & Signature Verification

Signature Header

Public Key for Verification

JavaScript Implementation

Migrating from V1 to V2

What Changed

Migration Steps

Best Practices

Testing Your Webhooks

Test Payload Example

Troubleshooting

Get Started

Astro

Fundamentals

SDKs

What's New

Support & Security

​Overview

Real-time Notifications

Secure Delivery

Reliable Delivery

Event-Specific Payloads

​Configuration

​Setting Up Your Webhook

​V2 Payload Structure

​Top-Level Fields

​Execution Info Structure

​Execution Events

​EXECUTION_STARTED

​EXECUTION_COMPLETED

​EXECUTION_FAILED

​EXECUTION_CANCELLED

​EXECUTION_PAUSED

​EXECUTION_RESUMED

​EXECUTION_AWAITING_CONFIRMATION

​Security & Signature Verification

​Signature Header

​Public Key for Verification

​JavaScript Implementation

​Migrating from V1 to V2

​What Changed

​Migration Steps

​Best Practices

​Testing Your Webhooks

​Test Payload Example

​Troubleshooting

Overview

Configuration

Setting Up Your Webhook

V2 Payload Structure

Top-Level Fields

Execution Info Structure

Execution Events

EXECUTION_STARTED

EXECUTION_COMPLETED

EXECUTION_FAILED

EXECUTION_CANCELLED

EXECUTION_PAUSED

EXECUTION_RESUMED

EXECUTION_AWAITING_CONFIRMATION

Security & Signature Verification

Signature Header

Public Key for Verification

JavaScript Implementation

Migrating from V1 to V2

What Changed

Migration Steps

Best Practices

Testing Your Webhooks

Test Payload Example

Troubleshooting