Facebook Chrome extension shows everything that the site knows about its users

Even if you’ve done your best to hide from Facebook, it probably has a huge dossier on you

A dog stands in front of a computer screen with a facebook page opened on it, on January 4, 2013 in Lille, Northern France (DENIS CHARLET/AFP/Getty Images)

The huge amount of data that Facebook collects on every one of its users has been exposed. And all it takes is a small Chrome extension.

The site’s ad tracking uses a huge amount of information about its users to provide marketing that it thinks will be both useful and successful. The algorithms that power that work are what has made Facebook such a huge success – but they remain mostly secret.

They are built from a huge set of different inputs. The site can watch, for instance, for people liking a particular status and then decide what sort of films they might be into. They might tag photos at a particular place, write their favourite music on their profile, comment on an article about a politician or change their relationship status – and each of those pieces of information are logged as ways of knowing more about a person.

And that information doesn’t necessarily need to come from Facebook. The Like buttons that are on almost every website can track for what people are looking at. And information on other apps like Instagram and WhatsApp are added to Facebook’s trove of data, meaning that people don’t necessarily need to use the Facebook app to controbute to their dossier.

Some of the data doesn’t even come from your interaction with Facebook at all. ProPublica reports that the company “buys data about its users’ mortgages, car ownership and shopping habits from some of the biggest commercial data brokers”, meaning that even if a user has done their best to stay unknown then Facebook’s dossier might be full of information.

For that reason, the site ProPublica built a special Chrome extension that allows a person to see everything that Facebook says it knows about its users. Some of it is highly specific – including the size of a person’s house or how many credit cards they have – and all of it is collected through the various interactions that people have with the site.