Notifications are the lifeblood of modern apps. They re-engage users, keep them informed, and build trust. But most apps rely solely on push notifications—without an in-app inbox, critical updates can easily be lost. Push notifications grab attention in the moment—perfect for a flight delay, an account alert, or a message from a teammate. But they’re fleeting—once dismissed, they’re gone.

I've been making apps since just after the App Store launched - it's actually what made me want to make apps in the first place. Looking back over this journey, it's amazing to see how much has changed. Let me take you through this evolution, because what's happening right now in mobile development is absolutely incredible.

Twilio powers communication for over 10 million developers and 300,000 businesses worldwide. As a leader in customer engagement, they’ve set the standard for seamless, scalable developer tools. But as their business grew, managing notifications became a challenge. Fragmented tools and workflows created inconsistencies and inefficiencies across teams. To solve this, Twilio turned to Courier—a platform designed to unify notifications and improve the developer experience at scale.

This month, we’re rolling out updates to our mobile SDKs with a focus on usability, reliability, and developer experience. Here’s a breakdown of the latest improvements for iOS, Android, React Native, and Flutter.

Sending a notification is simple—sending it at the right time is not. Whether it’s avoiding off-hours pings or managing users across time zones, timing matters. With Courier’s new Delivery Window, you can deliver messages at the perfect moment—without the overhead of custom scheduling code. Set the Rules, We’ll Handle the Rest The Delivery Window feature lets you define when notifications should go out, and Courier ensures they follow your rules.

Push notifications have carved their own niche as a powerful tool for continuous user engagement. Regardless of whether an app is actively in use, they deliver your messages straight to your user's device. Two useful tools to enhance your push notification strategy are Segment and Courier. In this article, we show you how to set up Courier to listen to your Segment events and then send push notifications to an Android device based on data from these events.

Once upon a time, SMS was the crowning achievement of communications technology. It combined email’s asynchronous archive of messages with a portable device, allowing anyone to send and receive information anywhere they were. Today, widespread mobile internet access has somewhat eclipsed the main functionality of SMS, but it remains a dominant form for communication in many markets and in particular business cases.

Perhaps because we are constantly swamped with push notifications, they can go overlooked as a messaging category. They are nevertheless an important medium of modern communication, and a more diverse one than you might think. Push notifications initialize interactions between a recipient and a sender, in an era of communication where response times are measured in seconds. Such high-frequency information requires effective distillation to remain efficient and to avoid flooding recipients with noise.

Firebase offers useful SDKs for both iOS and Android apps. It provides database services, analytics, and push notification tools. It also works with most programming languages, including Swift. If you're reading this article, you've probably already come across Firebase and its Cloud Messaging tool, which can be used to send push notifications to both Android and iOS devices.