While it’s no secret that Facebook Messenger tracks your location (it tells you this when you install the app and each time you start a new conversation), it may not sink in just how prevalent said tracking really is.

Interested in playing around a bit, technologist Aran Khanna recently wrote a Chrome extension for the Facebook Messenger page that scrapes all of the location data Facebook collects and plots it on a map. His findings are staggering, to say the least. 

While writing code for the extension, Khanna discovered that the latitude and longitude coordinates of location data have six decimal places of precision. This lets Facebook – and now, anyone – track a sender’s location to within less than three feet.

With his extension complete, Khanna wasted little time in seeing what sort of information he could gather about his friends. As revealed in his post on Medium, he was able to pinpoint the exact locations of people – their dorm and approximately where their room is located in the dorm, for example – with stunning accuracy.

Taking it a step further by keeping tabs on people for a couple of weeks, he was able to draw up a schedule of their daily lives. He even managed to do this for people he wasn’t friends with on the social network.

Needless to say, his extension is rather powerful (and creepy). But again, it’s all based on data that Facebook collects from its users. Anyone interested in trying it out can snag the extension by clicking here. The source code is also available on Github if you want to dig a bit deeper.

All images courtesy Aran Khanna, Medium