(BBC) – Some apps are sharing users’ health data. New research uncovers which apps lock down your privacy, and which don’t.

Stardust is a period tracking app that combines users’ menstrual cycles with astrology and horoscopes. It also makes bold privacy promises.

“Your data is private,” Stardust says on its website. “Period.”

The problem, according to a new report shared exclusively with the BBC, is you and Stardust may have different definitions of “private”.

The Mozilla Foundation, creator of the Firefox web browser, investigated the privacy practices of six popular period trackers: Flo, Clue, Stardust, Spot On, Period Calendar and Euki. (Read More)