If you are wondering how and which of the apps in your Android smartphone have used up all of your 4G LTE data pack that you paid for so reluctantly, then you may not be able to find any information unless you use a firewall app like GlassWire. It is essentially a firewall and network monitoring app for Android that also packs some extra features like warning you when you are about to finish up the data plan from your mobile network provider and showing alerts when a new app connects to the internet for the very first time.
GlassWire app for Android displays a graphical view of all the network activity in your phone. You can see how many bytes have been uploaded, how many have been downloaded, how much of mobile network data is used (for example, 3G or 4G LTE), how much of data from WiFi network is being used and so on. In addition, you can see all the apps that are connecting to the internet and their individual data use. All the data use is displayed in the graph against the timeline so you can see when the data was used and by which of the apps.
If you are on a limited data plan from your mobile network provider, then GlassWire can show alerts when you are about to use up all the data from the limited plan. By default, it alerts you when you are about to use 90% of the data. But you can always customize when the alert is to be shown. For example, if you have a 10 GB data plan from 4G network, then it will show alerts as soon as you finish using 9 GB of the data.
In the settings for the GlassWire app, you can customize the alerts and notifications that are used to tell you about the new apps that use the internet or when you use up most of the data from mobile network and more. You can toggle the alerts, notifications, sound and vibration when a new app connect to the internet, and when 90% of the data plan usage is reached.
Conclusion: GlassWire is a firewall for Android that helps you monitor the network activity in the smartphones. It can also alert and notify you when you use up 90% of the mobile network data plans.
You can get GlassWire for Android from https://play.google.com/store/apps/details?id=com.glasswire.android.