In December 2018, Privacy international exposed the dubious practices of some of the most popular apps in the world.Out of the 36 apps we tested, we found that 61% automatically transfer data to Facebook the moment a user opens the app. This happens whether the user has a Facebook account or not, and whether they are logged into Facebook or not. We also found that some of those apps routinely send Facebook incredibly detailed and sometimes sensitive personal data. Again, it didn’t matter if people were logged out of Facebook or didn’t have an account.
This sharing happens through the Facebook Software Development Kit (SDK), a set of software development tools that can be used to develop apps for a specific operating system. In an email to us on 29 December 2018, Facebook described how their product works: