Push notifications and in-app notifications are effective tools for maintaining user engagement and interaction within both mobile and web applications. Push notifications can be used to bring users back to an app, alert them of incomplete actions, or notify them of important events while they're away. In-app notifications, on the other hand, enhance the user experience by improving the onboarding process, converting freemium customers, and announcing new features at a relevant time. Combining in-app and push notifications often provides the best user experience, particularly for complex workflows. Platforms like Courier offer robust APIs and SDKs to integrate these technologies seamlessly across various notification channels, including email, SMS, chat apps, and more.