Firebase Notifications allows you to send notifications to your mobile app users. It’s free to use, and simple to develop against.
Here’s a video of me introducing it in just one minute:
Built on Firebase Cloud Messaging and the FCM SDK, Firebase Notifications (Notifications) provides an option for developers and organizations seeking a flexible notification platform that requires minimal coding effort to get started, and a graphical console for sending messages. Using the Notifications console GUI, you can reengage and retain your userbase, foster app growth, and support marketing campaigns.
To learn more about it, including how to build it, there’s a great session from Google IO 2016 here, where I demo notifications and just how little code I, as a lazy developer, had to write to get it to work!