Build a watch app using Flutter

You are a Flutter fan and have an idea about a watch app. Here is all you need to know — and it is a lot!

Do you want to use your Flutter skills to build a watch app? And send data to a watch face? Is a companion app on the phone required? Will your Flutter app be accepted on Google Play?

This post is based on my experience with the WatchGlucose for Wear OS app. Some Flutter knowledge is assumed. Some Kotlin skill helps but is not required.

What the app does

Some people with diabetes wear a sensor, which measures the level of glucose in their blood and sends it, once every minute, to a server.

What the app does is quite simple. Once every minute it fetches data — name, timestamp, glucose value, trend — from the server and displays it on the watch. It also shows the time of day, date, and battery level.

Similar logic could be used for an app that fetches stock data, weather data, or any data from a server with an API.

Being a Flutter fan, I asked myself: Can I build this with Flutter, if the watch uses Wear OS? Wear OS is based on Android. Why couldn’t a Flutter app for Android run on Wear OS and display the values from the server using regular widgets? The answer turned out to be a lot more complex than expected. I learned a lot from…