| Product | Knock |
| Website | knock.app |
| Category | Developer Infrastructure / Notifications |
| Channels | In-app, email, push, SMS, Slack, Discord, webhooks |
| Pricing | Free up to 10K notifications/month, Growth from $250/month |
What Is Knock?
Knock is a notification infrastructure platform. Instead of building in-app notifications, email triggers, push notifications, and Slack alerts separately, you define a notification workflow once and Knock delivers it across channels based on user preferences.
The problem: a single user action (“someone commented on your PR”) might need to send an in-app notification, an email if the user is offline, and a Slack message to the team channel. Building this requires separate integrations with SendGrid, Firebase, Slack, plus logic for user preferences, batching (“5 new comments” instead of 5 separate emails), and delivery tracking. Knock handles all of it through one API call.
Key Features
Cross-Channel Workflows
Define a notification workflow in Knock’s dashboard: “send in-app immediately, wait 5 minutes, if unread then send email.” Each channel (in-app, email, push, SMS, Slack) has its own template. The workflow engine handles timing, fallbacks, and channel selection.
User Preferences
Knock provides a preferences API and pre-built UI components. Users choose which notifications they want and on which channels. Your application doesn’t need to build a notification settings page — Knock provides one as an embeddable component.
Batching and Digests
Instead of sending “John commented,” “Jane commented,” “Alex commented” as three separate emails, Knock batches them into “3 new comments on your post.” The batching window is configurable per workflow and per channel.
In-App Feed
Knock provides pre-built React, iOS, and Android components for an in-app notification feed. Drop in the component, and your users get a notification bell with unread counts, mark-as-read, and real-time updates. The feed is powered by Knock’s API — no WebSocket infrastructure to build.
Who Is This For?
- SaaS products that need multi-channel notifications (in-app + email + Slack)
- Product teams that want to iterate on notification workflows without engineering work
- Applications replacing homegrown notification systems that have become unmaintainable
- Teams building collaborative tools that need real-time activity feeds
Pros
- One API call for multi-channel notifications
- Batching and digest built in
- Pre-built in-app feed components (React, iOS, Android)
- User preference management included
- Visual workflow builder for non-engineers
- Free tier covers early-stage products
Cons
- Growth plan ($250/month) is a jump from free
- Vendor lock-in on notification logic
- Requires separate email provider (SendGrid, Postmark)
- In-app components are React-first (limited framework support)
- Complex workflows can be hard to debug
Verdict
Notification infrastructure is one of those systems that every product needs, every team underestimates, and nobody enjoys maintaining. It starts as a few SendGrid API calls and grows into a tangle of channel logic, preference management, batching rules, and delivery tracking. Knock replaces that tangle with a managed service.
The pre-built in-app notification feed is the feature that saves the most engineering time. Building a real-time notification bell with unread counts, mark-as-read, and preference management is weeks of work. Knock provides it as a React component you drop in.
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