Facebook Messenger can track your location to within a metre, a developer has revealed after creating a program that allows others to pinpoint your whereabouts on a map.
Harvard computer science and mathematics student, Aran Khanna, has called his app Marauders Map after the Harry Potter books, as it allows people to discover the identity of Messenger app users, their location and previous movements.
The Chrome browser extension exploits the social network's default location settings on iOS and Android, which users must manually disable, and also uses GPS to place unsuspecting users on a map.
Writing on Medium, he said: "By simply looking at the cluster of messages sent late at night you can tell exactly where his [another user's] dorm is, and in fact approximately where his room is located in that dorm."
Looking into messages sent throughout the past few days, Khanna could build up a profile of other users' weekly schedules, predicting where one might be at any given time.
He could track the location of anyone he wasn't directly friends with too if they had sent messages to a group chat he was a member of.
He added: "Everyone I have shown this extension to has been anywhere from surprised to appalled that this much of their very personal data is online for their friends (and even complete strangers) to access.
"I decided to write this extension, because we are constantly being told how we are losing privacy with the increasing digitization of our lives, however the consequences never seem tangible.
"With this code you can see for yourself the potentially invasive usage of the information you share, and decide for yourself if this is something you should worry about."
At Facebook's request, he has now disabled the official version of the Chrome browser extension, but has left instructions on Github for other developers to run their own versions of the tool.
