App Version Tracker is a solution for developers who don’t publish their apps through the Play Store but still need a way to provide updates to users. With the Version Tracker API, you can easily compare your app's local version to the latest version on the server. The service offers a dashboard to manage all app versions, enabling you to update the version number in one place. Once updated, the new version is available to all users—it's that straightforward.
There is a frontend implementation for this in Flutter, which can be found at App Version Tracker Frontend.
You can find all the APIs used in this documentation.
An Android library for Version Tracker is also available here.