The 6 Best Notification Infrastructure Services for Product and Billing Alerts

For fast-moving SaaS and AI companies, delivering timely notifications to customers isn’t just a nice-to-have—it’s mission-critical. Whether you’re sending billing notifications, usage alerts, product updates, or lifecycle messaging, having robust notification infrastructure ensures reliability, scalability, and developer velocity.

At Orb, we see this need up close. Many of our customers implement billing notifications—alerting customers when they’re nearing usage thresholds, when invoices are ready, or when billing errors occur. Effective billing communication prevents surprises, builds trust, and keeps customers engaged. That’s why choosing the right notification infrastructure matters.

Below, we share six of the best notification infrastructure services in 2025 that can power your product, billing, and customer messaging workflows at scale.

1. Knock

Knock is a comprehensive notification infrastructure built by developers, for developers. It combines a powerful unified API with a dynamic workflow engine, enabling you to send product notifications and lifecycle messaging across channels including:

• Email
  
• SMS
  
• Push notifications
  
• In-app messaging
  
• Chat apps (Slack, Teams, WhatsApp, etc.)
  

What makes Knock stand out is its developer-first approach and elegant APIs for defining notification logic. For engineering teams tired of reinventing notification pipelines, Knock abstracts complexity so you can build and iterate faster.

Why it matters for billing notifications

For Orb customers, Knock integrates seamlessly to send automated billing communications—invoice ready alerts, payment failures, usage threshold warnings, and renewal reminders. With Knock’s workflow engine, you can ensure the right billing message reaches the right customer at the right time, in the channel they prefer.

In short, Knock isn’t just for product notifications—it becomes an operational backbone for revenue-critical communications.

2. Novu

Novu brands itself as the open-source notification infrastructure. Its popularity stems from offering a self-hostable alternative with a UI dashboard to manage templates and channels. Novu supports:

• Email
  
• SMS
  
• Push
  
• Chat (Slack, Teams)
  

For teams with strict self-hosting requirements or wanting full control over their notification pipeline, Novu provides flexibility. However, it requires more DevOps investment compared to fully managed platforms like Knock.

3. Courier

Courier positions itself as a notification routing and orchestration service. Its strength is routing notifications intelligently across multiple providers and channels with fallback logic to maximize delivery.

Courier offers:

• A no-code notification designer
  
• Multi-channel orchestration (email, SMS, push, chat)
  
• Built-in analytics and logs
  

While Courier focuses heavily on design flexibility and routing, it may require deeper integration work to implement programmatic notification workflows at scale.

4. SuprSend

SuprSend provides a notification infrastructure designed to unify fragmented notification logic. It focuses on enabling product teams to orchestrate notifications without engineering bottlenecks.

Key features include:

• Unified API for all channels
  
• Campaign and template management
  
• Event-based workflows
  

For companies that want a balanced approach between developer APIs and marketer-friendly campaign tools, SuprSend offers versatility.

5. Fyno

Fyno brands itself as a “notifications control plane.” Its focus is on abstracting integrations with different providers and giving observability into delivery performance.

Highlights:

• Multi-channel provider integrations
  
• Event-based triggers
  
• Delivery monitoring and analytics
  

Fyno is suitable for engineering teams wanting granular observability and routing flexibility across providers.

6. NotificationAPI

NotificationAPI is a developer tool for quickly adding notifications to your app. Its API-first approach allows you to integrate email, SMS, push, and chat notifications with minimal setup.

While less comprehensive in workflow orchestration than Knock or Courier, NotificationAPI is lightweight and effective for straightforward notification needs.

Honorable Mention: EngageSpot

EngageSpot focuses on product notifications, particularly in-app and push, with easy integration for SaaS platforms. It may not offer as robust multi-channel orchestration as others on this list, but is a popular choice for fast integration of in-app notifications.

Choosing the right notification infrastructure for billing and product messaging

When selecting a notification infrastructure, consider:

1. Channels – Does it support all required channels (email, SMS, in-app, chat apps)?
   
2. Workflow flexibility – Can it handle event-driven workflows, fallback logic, and conditional triggers?
   
3. Scalability – Is it reliable for mission-critical notifications like billing communications?
   
4. Developer experience – Does it offer intuitive APIs, webhooks, and SDKs to accelerate integration?
   

How Orb and Knock work together

At Orb, we empower companies with robust usage-based billing, plan management, and revenue operations infrastructure. Customers can use Orb to calculate usage and generate invoices, while leveraging Knock to deliver:

• Invoice ready notifications
  
• Payment failure alerts
  
• Usage threshold warnings
  
• Renewal reminders
  

This combination ensures customers always know what to expect—driving trust, reducing billing disputes, and enhancing product experience.

Final thoughts

Billing notifications aren’t just operational—they’re part of your product experience and revenue communication strategy. Tools like Knock make it easy to build scalable, reliable, and personalized notification workflows that integrate seamlessly with your billing stack.

If you’re building with Orb and want to optimize your billing notifications, explore how Knock can accelerate your deployment.