Threema claims to be the most secure Swiss encrypted messaging and work collaboration app in the world.
It is made in Switzerland where privacy is taken seriously and uses crazy encryption trusted by 12 million users.
You can use it for free or get a cheap lifetime plan that will give you access to more features. Calling and chatting is possible and if yo are a content creator worried about your privacy and the things you do online Threema is then for you.
It is available for all platforms, IOS, Android, Web, Linux, Windows, and Mac OS and the app or software is awesome and lightweight.