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Alex Spinov
Alex Spinov

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Knock Has a Free API — Here's How to Build a Notification System in 15 Minutes

#knock #notifications #api #webdev

An engineer I know spent a month building a notification system. Email templates, push notifications, in-app feed, preference management, batching. Then the PM asked for Slack notifications too. He rewrote it all with Knock in one afternoon.

What Knock Offers for Free

Knock free tier:

  • 10,000 notifications/month
  • Unlimited channels — email, push, SMS, Slack, in-app
  • Workflow builder — visual notification logic
  • Preference management — users control what they receive
  • Batching and digests — 'You have 5 new comments' instead of 5 emails
  • In-app feed component — drop-in React component
  • Idempotency — no duplicate notifications

Quick Start 

npm install @knocklabs/node
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const { Knock } = require('@knocklabs/node');
const knock = new Knock(process.env.KNOCK_API_KEY);

// Send a notification
await knock.workflows.trigger('new-comment', {
  recipients: ['user_123'],
  data: {
    commenter: 'Alice',
    comment: 'Great post!',
    post_title: 'How to Build APIs',
    post_url: 'https://example.com/post/123'
  }
});
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Define Workflows (Visual or API) 

// A workflow can send to multiple channels with logic
await knock.workflows.trigger('order-update', {
  recipients: ['user_456'],
  data: {
    order_id: 'ORD-789',
    status: 'shipped',
    tracking_url: 'https://track.example.com/789',
    estimated_delivery: '2026-04-02'
  }
});

// Knock workflow (configured in dashboard):
// 1. Send in-app notification immediately
// 2. Wait 5 minutes
// 3. If not read → send email
// 4. Wait 1 hour
// 5. If not read → send push notification
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In-App Feed (React) 

import { KnockProvider, KnockFeedProvider, NotificationIconButton, NotificationFeedPopover } from '@knocklabs/react';
import '@knocklabs/react/dist/index.css';

function App() {
  const [isVisible, setIsVisible] = useState(false);
  const buttonRef = useRef(null);

  return (
    <KnockProvider apiKey="pk_YOUR_PUBLIC_KEY" userId="user_123">
      <KnockFeedProvider feedId="YOUR_FEED_ID">
        <NotificationIconButton
          ref={buttonRef}
          onClick={() => setIsVisible(!isVisible)}
        />
        <NotificationFeedPopover
          buttonRef={buttonRef}
          isVisible={isVisible}
          onClose={() => setIsVisible(false)}
        />
      </KnockFeedProvider>
    </KnockProvider>
  );
}
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User Preferences 

// Set user preferences
await knock.users.setPreferences('user_123', {
  channel_types: {
    email: true,
    push: true,
    sms: false // User opted out of SMS
  },
  workflows: {
    'marketing-updates': { channel_types: { email: false } }, // No marketing emails
    'order-updates': true // All channels for orders
  }
});

// Get preferences
const prefs = await knock.users.getPreferences('user_123');
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Batching (Digest Notifications) 

// Instead of 10 separate 'new follower' notifications:
// Knock batches them into: 'Alice, Bob, and 8 others followed you'

// Just trigger normally — Knock handles batching in the workflow
await knock.workflows.trigger('new-follower', {
  recipients: ['user_123'],
  data: { follower_name: 'Alice', follower_avatar: 'https://...' }
});
// Configure batch window (e.g., 15 minutes) in the workflow builder
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REST API 

# Trigger a workflow
curl -X POST 'https://api.knock.app/v1/workflows/new-comment/trigger' \
  -H 'Authorization: Bearer sk_YOUR_SECRET_KEY' \
  -H 'Content-Type: application/json' \
  -d '{
    "recipients": ["user_123"],
    "data": { "commenter": "Alice", "comment": "Nice work!" }
  }'

# Get user's notifications
curl 'https://api.knock.app/v1/users/user_123/feeds/YOUR_FEED_ID' \
  -H 'Authorization: Bearer sk_YOUR_SECRET_KEY'

# Mark notifications as read
curl -X POST 'https://api.knock.app/v1/users/user_123/feeds/YOUR_FEED_ID/read' \
  -H 'Authorization: Bearer sk_YOUR_SECRET_KEY'
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Perfect For

  • SaaS apps — in-app + email notifications
  • Marketplaces — order updates across channels
  • Social platforms — follow/like/comment notifications with batching
  • Developer tools — build alerts, CI/CD notifications

Need to monitor web changes and get notified? Check out my web scraping actors on Apify — automated monitoring and data collection.

Need a custom notification system? Email me at spinov001@gmail.com.

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