Webhooks

Webhooks allow external services to trigger workflow execution from external webhooks by sending HTTP requests to your workflow. Sim supports two approaches for webhook-based triggers.

Generic Webhook Trigger

The Generic Webhook block creates a flexible endpoint that can receive any payload and trigger your workflow:

How It Works

1. Add Generic Webhook Block - Drag the Generic Webhook block to start your workflow
2. Configure Payload - Set up the expected payload structure (optional)
3. Get Webhook URL - Copy the automatically generated unique endpoint
4. External Integration - Configure your external service to send POST requests to this URL
5. Workflow Execution - Every request to the webhook URL triggers the workflow

Features

• Flexible Payload: Accepts any JSON payload structure
• Automatic Parsing: Webhook data is automatically parsed and available to subsequent blocks
• Authentication: Optional bearer token or custom header authentication
• Rate Limiting: Built-in protection against abuse
• Deduplication: Prevents duplicate executions from repeated requests

Trigger Mode for Service Blocks

Alternatively, you can use specific service blocks (like Slack, GitHub, etc.) in "trigger mode" to create more specialized webhook endpoints:

Setting Up Trigger Mode

1. Add Service Block - Choose a service block (e.g., Slack, GitHub, Airtable)
2. Enable Trigger Mode - Toggle "Use as Trigger" in the block settings
3. Configure Service - Set up authentication and event filters specific to that service
4. Webhook Registration - The service automatically registers the webhook with the external platform
5. Event-Based Execution - Workflow triggers only for specific events from that service

When to Use Each Approach

Use Generic Webhook when:

• Integrating with custom applications or services
• You need maximum flexibility in payload structure
• Working with services that don't have dedicated blocks
• Building internal integrations

Use Trigger Mode when:

• Working with supported services (Slack, GitHub, etc.)
• You want service-specific event filtering
• You need automatic webhook registration
• You want structured data handling for that service

Supported Services for Trigger Mode

The following service blocks support trigger mode:

• Slack - Messages, mentions, reactions
• GitHub - Push, PR, issue events
• Airtable - Record changes
• Telegram - Bot messages and commands
• Gmail - Email notifications
• WhatsApp - Messaging events
• Jira - Issue updates, comments
• Linear - Issue state changes
• Notion - Page updates

Security and Best Practices

Authentication Options

• Bearer Tokens: Include Authorization: Bearer <token> header
• Custom Headers: Define custom authentication headers

Payload Handling

• Validation: Validate incoming payloads to prevent malformed data
• Size Limits: Webhooks have payload size limits for security
• Error Handling: Configure error responses for invalid requests

Testing Webhooks

1. Use tools like Postman or curl to test your webhook endpoints
2. Check workflow execution logs for debugging
3. Verify payload structure matches your expectations
4. Test authentication and error scenarios

Common Use Cases

Real-time Notifications

• Slack messages triggering automated responses
• Email notifications for critical events

CI/CD Integration

• GitHub pushes triggering deployment workflows
• Build status updates
• Automated testing pipelines

Data Synchronization

• Airtable changes updating other systems
• Form submissions triggering follow-up actions
• E-commerce order processing

Customer Support

• Support ticket creation workflows
• Automated escalation processes
• Multi-channel communication routing