The Wall Street Journal conducted an investigation recently were it took 101 apps on the iPhone and Android smartphones and looked at the information that the apps shared with third parties about the user. The WSJ found that 56 of the apps in the investigation sent the smartphones unique device ID to other companies without the user knowing or agreeing to the sharing. 47 of the apps sent the phones location to third parties, and five of the apps sent age, gender, and personal details to outsiders.
The data is mostly sent to ad companies so they can tailor ads to the user's history for better results. The WSJ says that the app that shares the most personal info is an iPhone app called TextPlus 4. The app sent the unique ID of the device to eight ad companies and also sent the zip code, user's age, and gender to two more firms.