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Comparing Courier vs Knock: Analysis of Notification Systems

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Courier makes it easy to send SMS, email, push and in-app notifications with a single API call. We have a REST API, client SDKs and Docs that you'll love πŸ’œ


As development teams look at Courier to improve the way they send notifications to users, it’s sometimes necessary to compare Courier with other offerings in the communications space.

To start with, it makes sense to better familiarize yourself with Courier. You can sign up for Courier for free or, for a more detailed understanding of how Courier compares in your unique environment, you can contact us.

To make this analysis as fair as possible, we rely extensively on feedback from development teams that have used Courier and rather than our own opinions. We go into detail on the features as the differences might be nuanced (but quite important). If you have any questions or feedback, please reach out. Now, let's dive into the details.


Unlike marketing notifications, product notifications are a core component of how your users experience your application. Whether it’s a push notification to bring users back into the app, or a password reset notification, or an email that prompts a user to take action β€” these notifications need to work with your tech stack to trigger a notification at the right time, with the right information, on the right channel.

It’s important that a notification system support the channels and providers that your users expect and that best suit each use case. And there are a range of other integrations that are important for making each notification feel like a part of the application experience.

Feature comparison:

Provider integrations across email, SMS, push, chat, and in-app2348
Email template import (e.g. SendGrid, Mandrill)βŒβœ”
Customer data platform (CDP)Β  integrationsβœ”βœ”
Content integrations (eg. AI-generated content, translation)βŒβœ”
Reverse ETL (eg. Census, Hightouch)βŒβœ”
Observability integrationsLimitedβ€”Datadog onlyβœ”
SSO integrationsβœ”βœ”

SDKs for in-app notification center and user preferences

While supporting existing channels and providers is important, it’s becoming increasingly necessary to offer a notification experience inside of your web or mobile app. Typically such an experience consists of a notification inbox that works alongside mobile push and web-based popup messages (also called β€œtoast” messages). This works in tandem with a user preferences center, where each user can configure channels they want to receive notifications on and message frequency for each notification topic.

Feature comparison:

Notification inbox web SDKsβœ”βœ”
Notification inbox mobile SDKs for iOS and AndroidβŒβœ”
Synchronized message status across web and mobile inboxesβŒβœ”
Preferences center, fully hostedβŒβœ”
Preferences API, built to spec (headless)βœ”βœ”

Customization per account, with multi-tenancy

For businesses that need to customize the experience for each of their customers, features like unique branding are important for allowingΒ white-label communications, where each account can customize their own unique branding and content. A few critical areas of customization include:

  1. Creating and editing new brands via the API or directly from a web application UI.
  2. Adjusting the look and feel of client-side components that will be embedded into applications, so that each sub-customer can directly update branding themselves (example screenshot).
  3. Enabling developers to send a simplified JSON document to the notification system (e.g. Courier Elemental), making it possible for each customer to completely customize the content of the messages they’re sending. The messages should also include support for rich elements like images, buttons, variables, loops, and others. The rich content needs to work across all notification channels and automatically get rendered appropriately so that the same mechanism is used to let each account customize messages in one channel (say, Slack) as in another channel (like email).
  4. Robust tenant segmentation using list patterns to subdivide tenants’ accounts into teams (or other units) within that tenant. For example, you might have a need to message all users within all teams of the customer β€œacme” (which would be covered by the wildcard acme.** in Courier), or you might need to send a message to all admins across all customers (in Courier the wildcard for this would be *.admins ).

Feature comparison:

Global customizable brandingβœ”βœ”
Multiple tenant per account, user & preference attributionβœ”βœ” Beta
White-label multi-tenant customer control over brandingβŒβœ”
Multi-layer tenant categorizationβŒβœ”
Advanced message customization across channels (Elemental)βŒβœ”

Content localization within notifications

For applications that support users across international borders, localizing the design and content for each notification is crucial.

While basic localization is a core part of any notification service, there are significant differences in each approach and flexibility provided by each solution.

Content and design internationalization should not only be available in the template designer of the web application, but also provide advanced capabilities to enable language translation with any third-party translation services like Crowdin. The notification system should be designed to support the unique characteristics of this asynchronous publishing workflow. When someone publishes a new version of a message template β€” for any channel β€” the internationalization tooling should automatically start the translation process in coordination with that service. And it should handle delays from that service, whether translation is provided automatically or via human translators β€” pausing publication while waiting for the translation process to be completed.

Feature comparison:

Translation in the application UI template designerβœ”βœ”
Programmatic translation designed to support third-party translation serviceβŒβœ”

Web interface in addition to the API

While notification systems focus primarily on the developer experience (DX), it’s often just as important to balance that with an intuitive web interface to manage and design templates, review logs across channels, build notification sequences that kick off from events that originate in third-party customer data tools like Segment, and so on. It allows non-technical teammates to make changes, freeing developers from repetitive tasks and the time involved to coordinate, review, and get approval for these changes.

This is an area where Courier consistently beats Knock through the right balance of both developer experience and web-based tooling. While this is a subjective rating, we encourage you to log in to Courier to see the value of the web interface yourself. Also check out more information about how we’re envisaging the future design direction of the web interface.

Security and compliance

Notifications send personalized content and data straight to a user’s device via email, SMS, push, etc. β€” which means security, data privacy, and compliance are fundamental requirements for notification infrastructure.

Feature comparison:

SOC 2 type 2 certification, GDPR compliance, HIPAA complianceβœ”βœ”
Live security portal and reportingβŒβœ”
SAML-based SSO with RBACβœ”βœ”
Dedicated SSO provider integrationβŒβœ”
API key revocation supportβŒβœ”
Customizable RBAC rolesβŒβœ”

Product maturity and advanced features

The product you choose must offer a complete feature set for notification delivery as well as other functionality that you might need to build out the desired user experience.

Courier's extensive features, like Digests, Batching, Throttling of events, and the Bulk Send feature, provide flexibility and control that Knock can't match.

Additionally, Courier allows you to set account-level limits, controlling the volume of messages sent to a user or a channel. This level of granularity and control is absent in Knock's offering.

Feature comparison:

Event throttlingβœ”βœ”
Bulk send featureβŒβœ”
Time-configured batch sendβœ”βœ”
User-defined message digestingβŒβœ”
Account-level send limit controlsβŒβœ”
Option for manual one-time notification send from the web UIβŒβœ”

Client libraries supported

The breadth of support for native SDKs across popular programming languages is a good indication of product maturity and developer focus.

React NativeβŒβœ”

Financial health

While overall stability of a company can feel subjective, there are some clear indicators that Courier is in a stronger position than any other player in this space. Courier is backed by top-tier investors like Bessemer, Google Ventures, Matrix Partners, and Y Combinator. It is also funded by both Twilio and Slack β€” early recognition that these communications APIs alone are not enough to support the complex logic behind most notification use cases.


When deciding on the right notification infrastructure for your organization, careful consideration should be given to the platform's compatibility with your tech stack, customization abilities, localization support, user empowerment, security features, and maturity, and the financial stability of the associated company that built and maintains the solution.

In our comparison between Courier and Knock, it's evident that Courier consistently outperforms in these areas. There are good examples of companies like LaunchDarkly, Comcast, Lattice, ApartmentList, and Contentful, who choose to power their product’s notifications using Courier.

We hope this guide was helpful. Choose wisely!

You can signup for Courier for free or, for a more detailed understanding of how Courier can add value for your unique environment, contact us

Create Your Free Developer Account

Courier makes it easy to send SMS, email, push and in-app notifications with a single API call. We have a REST API, client SDKs and Docs that you'll love πŸ’œ


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