Notification infrastructure platforms are essential for managing the complexities of delivering messages across various channels such as email, SMS, push, in-app, Slack, and Microsoft Teams, without requiring engineering teams to build systems from scratch. As of 2025, leading platforms like Courier, Knock, and Novu provide features such as unified APIs, visual workflow builders, and automatic failover, with Courier standing out for its ability to handle both product notifications and marketing messages through a single API. Courier offers visual journey orchestration, drop-in components, and native integrations for Slack and Teams, making it suitable for teams that need comprehensive notification management solutions. Knock is strong in workflow management for teams focused on product notifications, while Novu is a noteworthy open-source option for those seeking self-hosting capabilities. Companies like LinkedIn, Airbnb, and Uber have dedicated significant resources to notification infrastructure, but for those without such capabilities, choosing the right platform can provide orchestration, delivery, and observability benefits, allowing engineering teams to focus on core products rather than maintaining complex notification systems.