lindy-webhooks-events

Lindy Webhooks & Events

Overview

Lindy supports webhooks in two directions: Inbound (Webhook Received trigger wakes an agent) and Outbound (HTTP Request action calls your API). This skill covers both patterns, plus the callback pattern for async two-way communication.

Prerequisites

• Lindy account with active agents
• HTTPS endpoint for receiving callbacks (if using outbound/callback patterns)
• Completed lindy-install-auth setup

Webhook Architecture

INBOUND (your system triggers Lindy):
[Your App] --POST--> https://public.lindy.ai/api/v1/webhooks/<id>
                         ↓
                    [Lindy Agent Wakes Up]
                         ↓
                    [Processes with LLM]
                         ↓
                    [Executes Actions]

OUTBOUND (Lindy calls your system):
[Lindy Agent] --HTTP Request action--> https://your-api.com/endpoint
                                            ↓
                                       [Your Handler]

CALLBACK (two-way async):
[Your App] --POST with callbackUrl--> [Lindy Agent]
                                          ↓
[Your App] <--POST to callbackUrl-- [Lindy: Send POST to Callback]

Instructions

Step 1: Create Webhook Received Trigger

1. In your agent, click the trigger node
2. Select Webhook Received
3. Lindy generates a unique URL:

   https://public.lindy.ai/api/v1/webhooks/<unique-id>
   

4. Click Generate Secret — copy immediately (shown only once)
5. Configure follow-up processing mode:
   • Process in workflow: Handle in current workflow
   • Spawn separate task: Each webhook creates a new task
   • Discard follow-ups: Ignore subsequent requests while processing

Step 2: Access Webhook Data in Workflow

Reference incoming webhook data in any subsequent action field:

Variable	Description	Example
{{webhook_received.request.body}}	Full JSON payload	{"event": "order.created", ...}
{{webhook_received.request.body.event}}	Specific field	"order.created"
{{webhook_received.request.headers}}	All HTTP headers	{"content-type": "application/json"}
{{webhook_received.request.query}}	URL query params	{"source": "stripe"}

Step 3: Implement Webhook Sender

// webhook-sender.ts — Trigger Lindy agents from your application
interface LindyWebhookPayload {
  event: string;
  data: Record<string, unknown>;
  callbackUrl?: string;
  metadata?: Record<string, unknown>;
}

async function triggerLindy(payload: LindyWebhookPayload): Promise<void> {
  const response = await fetch(process.env.LINDY_WEBHOOK_URL!, {
    method: 'POST',
    headers: {
      'Authorization': `Bearer ${process.env.LINDY_WEBHOOK_SECRET}`,
      'Content-Type': 'application/json',
    },
    body: JSON.stringify(payload),
  });

  if (!response.ok) {
    throw new Error(`Lindy webhook failed: ${response.status}`);
  }
}

// Usage examples:
await triggerLindy({
  event: 'customer.support_request',
  data: { email: 'user@co.com', subject: 'Billing question', body: '...' },
});

await triggerLindy({
  event: 'lead.qualified',
  data: { name: 'Jane Doe', company: 'Acme', score: 85 },
  callbackUrl: 'https://api.yourapp.com/lindy/callback',
});

Step 4: Implement Callback Receiver

When you include a callbackUrl in your webhook payload, the agent can respond using the Send POST Request to Callback action:

// callback-receiver.ts
import express from 'express';

const app = express();
app.use(express.json());

// Receive Lindy agent results
app.post('/lindy/callback', (req, res) => {
  // Verify authenticity
  const auth = req.headers.authorization;
  if (auth !== `Bearer ${process.env.LINDY_WEBHOOK_SECRET}`) {
    return res.status(401).json({ error: 'Unauthorized' });
  }

  // Respond immediately (Lindy expects a quick response)
  res.json({ received: true });

  // Process async
  handleCallback(req.body);
});

async function handleCallback(data: any) {
  console.log('Lindy callback:', data);

  // Example: Agent analyzed a support ticket
  const { classification, sentiment, draft_response, confidence } = data;

  if (confidence > 0.9) {
    await sendAutoResponse(draft_response);
  } else {
    await escalateToHuman(data);
  }
}

Step 5: Configure HTTP Request Action (Outbound)

For Lindy agents that call your API as an action step:

1. Add action: HTTP Request
2. Configure:
   • Method: POST (or GET, PUT, DELETE)
   • URL: https://api.yourapp.com/endpoint
   • Headers (Set Manually):

     Content-Type: application/json
     Authorization: Bearer {{your_api_key}}
     

   • Body (AI Prompt mode):

     Send the analysis result as JSON with fields:
     classification, sentiment, summary
     Based on: {{previous_step.result}}
     

Step 6: Add Trigger Filters

Prevent unnecessary agent triggers:

Filter: body.event equals "order.created"
  AND body.data.amount greater_than 100

This ensures the agent only processes high-value orders, saving credits.

Event Patterns

Pattern: Webhook + Slack Notification

Webhook Received → Condition (classify event type)
  → "billing" → Search KB → Draft Reply → Send Email + Slack Alert
  → "technical" → Agent Step (investigate) → Create Ticket → Slack Alert
  → "other" → Forward to team inbox

Pattern: Webhook + Callback

Webhook Received (with callbackUrl) → Process Data → Run Code
  → Send POST Request to Callback (returns results to caller)

Pattern: Webhook + Multi-Agent

Webhook Received → Agent Send Message (to Research Lindy)
  → Research Lindy completes → Agent Send Message (to Writer Lindy)
  → Writer Lindy completes → Send Email with final output

Monitoring Triggers

Lindy provides built-in monitoring triggers:

• Task Completed: Fires when an agent completes a task
• Use this to build observability pipelines: Agent completes → log to sheet → alert on failures

Error Handling

Issue	Cause	Solution
401 on webhook send	Wrong or missing Bearer token	Verify secret matches Generate Secret value
Webhook URL returns 404	Agent deleted or URL changed	Re-copy URL from agent trigger settings
Callback not received	callbackUrl unreachable	Ensure HTTPS, public endpoint, no firewall
Duplicate processing	Webhook retried	Implement idempotency with event IDs
Payload too large	Body exceeds limit	Reduce payload size, send references not data

Security

• Always use HTTPS for webhook URLs
• Generate and verify webhook secrets on every request
• Rotate secrets every 90 days
• Log all webhook attempts (including rejected ones)
• Rate limit your webhook sender to prevent flooding

Resources

• Webhooks Documentation
• Webhook Triggers Academy
• Calling Any API

Next Steps

Proceed to lindy-performance-tuning for agent optimization.