A Mozilla Foundation investigation found major differences in how six popular period tracking apps handle reproductive health and identifying data. Stardust was the only app found sending detailed health information to another company, while Euki kept users’ health records entirely on their devices. Its period tracker privacy research considered what information each app collected, where it was stored and which outside services received it. Stardust Sent Health Data to RudderStackThe investigation found that Stardust sent reproductive health information to analytics provider RudderStack, which was not identified in the app’s privacy policy. Flo and Clue also received relatively favourable assessments because Mozilla did not find either app sharing health information with third parties.