With OpenSignal you can map cellularcoverage, find Wi-Fi hotspots, test and improve your reception & get faster data. Signal compass points you in the direction your signal is coming from, just walk towards it! WiFi map allows you to easily locate nearby public networks. Coverage maps allow you see the best/worst places for signal. Speedtest feature allows you to see the true speed of your connection (download, upload & latency). NetworkRank shows which carrier is best in your area. See local cell towers. Free and ad-free
Android OS sometimes kills some applications which you need or want to have running. You can select which applications you want to prevent from being killed.
Measure the charging and discharging current of your battery. The app works on Android 4.0.3+ devices. Not every device is supported because there are devices which