Using Threema for years on all my devices (pc & mobile (Linux, iPhone, etc)). Works always perfectly. Never ever had any problems! Everyone I know has Threema for their security and privacy, nothing else. Yet, Threema is not just an alternative or a substitute for other mainstream free apps. Actually, there is no substitute for Threema, because there can only one be ‘the best’. With Threema, only you know your true identity (…or your contacts, if you want). Threema costs just a few €’s, but then one gets the best & most secure messenger on this planet!
Update April 8, 2024: actually, I have proof that Threema is the safest and most secure E2EE messaging app, ever. I knew it! I repeat, there can be ONLY ONE the best. There’re no hidden trackers or any other ‘hocus-pocus’ things. Threema is a 100% honest app, one can trust. Thank you for making the Threema app possible!