Aran Khanna's app called the Marauder's Map, (yes, just like the one Harry Potter used) took data from Facebook Messenger to map users' location when they sent messages. The computer science and math student at Harvard University in Massachusetts, US, posted about his app on social media sites Reddit and Medium in May end this year and soon it went viral.
A default setting in the app (which can be disabled) allows the location of an individual to be sent along with chat messages. When Khanna realised several of the messages he had sent his friends on chat had his location attached to it, he wrote a piece of code which uses all the location data from messages and plots it on a map.
The app caught the attention of Facebook and Khanna was asked to disable it.
However, before it was disabled, the extension was downloaded more than 85,000 times and "shared on over 200 publications", according to Khanna.
