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Period tracking app refuses to disclose data to American authorities
(www.newsweek.com)
This is a most excellent place for technology news and articles.
Simple. Most FOSS are built for privacy and thus do not harvest data to send to some server somewhere in the world for whatever obscure reason. The data is locally stored on your device and stays and dies there.
No callback, no selling nor surrending data.
Personally speaking, I'd quicker have all data banks destroyed than surrendered to whatever purposes, if I ever decided to build an aplication that somehow compiled data.