There are nearly 4,000 different types of devices running Android, OpenSignalMaps has found. More than 1,300 of them have custom ROMs that tweak the android.build model. Android brands are almost as diverse as the models, OpenSignalMaps discovered. Further, the application programming interface level, meaning the Android version, has also become more fragmented over time. These facts bear out the general impression that Android is a fragmented operating system. However, that's not necessarily a bad thing.