Express.js API that publishes user events to Knock.app for intelligent notification orchestration.

Watch the complete setup and demo - Step-by-step video explaining the architecture, code walkthrough, and Knock dashboard configuration.

Event Publisher Pattern: API publishes classified events to Knock. Knock workflows handle all notification logic including conditional delivery and smart scheduling based on user profile data.

API Event → Knock Workflow → Conditional Logic → Scheduled Notification

npm install
cp .env.example .env
# Add your KNOCK_SECRET_KEY
npm start

knock-notifications/
├── routes/
│   └── users.js          # User event endpoints
├── server.js             # Express server
├── package.json          # Dependencies
├── .env.example          # Environment template
└── README.md             # This file

1. API publishes events (not direct notifications)
2. Knock receives event and checks user profile data
3. Workflow executes conditionally based on field existence
4. Notifications scheduled using user's actual timestamps

Publishes user_created event with user profile data.

curl -X POST http://localhost:3000/api/users/onboard \
  -H "Content-Type: application/json" \
  -d '{
    "userId": "user123",
    "userEmail": "[email protected]",
    "userName": "John Doe",
    "userCreatedAt": "2025-01-15T10:30:00Z",
    "planType": "premium",
    "signupSource": "mobile"
  }'

Response:

{
  "success": true,
  "user_profile": {
    "id": "user123",
    "email": "[email protected]",
    "name": "John Doe",
    "created_at": "2025-01-15T10:30:00Z",
    "plan_type": "premium",
    "signup_source": "mobile"
  }
}

Generic event publisher for any workflow trigger.

curl -X POST http://localhost:3000/api/users/event \
  -H "Content-Type: application/json" \
  -d '{
    "userId": "user123",
    "eventType": "first_login",
    "eventData": {"device": "mobile"}
  }'

Retrieve user profile from Knock.

Update user profile via user_profile_updated event.

1. Branch Step: Check if recipient.created_at exists (not_empty operator)
2. Delay Step: Fixed interval or calculated from timestamp
3. Email Step: Welcome email with user data

if (recipient.created_at exists) {
  wait(delay_duration)
  send_welcome_email()
} else {
  do_nothing()
}

• {{ recipient.name }} - User's name
• {{ recipient.email }} - User's email
• {{ recipient.plan_type }} - Subscription plan
• {{ recipient.signup_source }} - How they signed up
• {{ recipient.created_at }} - Account creation timestamp

KNOCK_SECRET_KEY=sk_test_your_knock_api_key
PORT=3000

• Decoupled: API doesn't contain notification logic
• Flexible: Add new workflows without code changes
• Smart: Workflows access full user profile context
• Conditional: Logic based on user data existence
• Scalable: Knock handles delivery, retries, and scheduling

Unlike traditional "send in X time from now" approaches, this system uses the user's actual creation timestamp for scheduling:

// Traditional approach - delay from current time
delay_until: now() + 2_days

// This system - delay from user's creation time
delay_until: recipient.created_at + 2_days

This enables accurate lifecycle messaging regardless of when events are triggered.

• Express.js - API server
• Knock.app - Notification orchestration
• Event-driven architecture - Scalable pattern