For six months, the team behind the Android app OpenSignalMaps tracked the devices where their app ended up, and their findings paint a good picture of just how difficult it is for Android developers to deal with fragmentation. After 681,900 downloads in 195 countries, OpenSignalMaps was running on a staggering 3,997 distinct models. That means in order to ensure a consistent experience for all of their users, the development team would have had to test it for nearly 4,000 unique devices.
To see a visual representation of the problem, check out the graphs and graphics in the OpenSignalMap blog post.