After analyzing 34 Android apps, Privacy International research uncovered 23 apps that shared users' data with Facebook without consent. The data was shared the moment a user opened the app, which included those users without a Facebook account.
The research took place in response to the Cambridge Analytica scandal which broke in early 2018 and saw 50 million users' data shared by Facebook without their consent. This was far from the end of the controversy, however, as the social media giant faced fresh allegations in December 2018 when it was revealed that it also gave Netflix and Spotify the ability to read and even delete users' private messages.
"Facebook routinely tracks users, non-users and logged-out users outside its platform through Facebook Business Tools," said Privacy International. "App developers share data with Facebook through the Facebook Software Development Kit (SDK), a set of software development tools that help developers build apps for a specific operating system."
The Android apps that were analyzed have between 10–500 million users and were tested by the charity between August and December 2018. Apps that were found to be sharing data with Facebook included Indeed, Skyscanner and Duolingo.
Facebook responded to Privacy International to tell them that sharing data is a "common practice for many companies" and argued that it is helpful for both the users and the companies involved.
"This information is important for helping developers understand how to improve their apps and for helping people receive relevant advertising in a privacy-protective way," Facebook said.
"We do this in a transparent manner by explaining the practice through our data policy and cookies policy, and by using Google's advertising identifier, which can be controlled centrally by people using their device settings," it added.