AppNotifier is a free Android utility that brings back app update and install notifications that were removed by Google Play. With AppNotifier, you can receive notifications each time an app is installed or updated on your device. You can also choose whether to receive notifications for apps from Google Play or sideloaded apps.

The app works by generating notifications using data from the apps on your device, rather than the Play Store itself. However, there are certain limitations to this approach. For example, AppNotifier does not detect when apps are in the middle of installing, so there may be a delay between when an app downloads and when the install or update notifications appear. Additionally, if an app's name differs between the Play Store listing and the actual app on your device, the latter will be used.

Overall, AppNotifier is a useful tool for those who miss the convenience of app update and install notifications. However, it's important to keep in mind its limitations and the potential for duplicate notifications if the Play Store's notification channel for "Updated apps" is not disabled in the Android system settings.