Actually one of my favorite apps along with Wire, I’m actually a moderator (Profile here) on the official online community for Cryptomator which provides everything from support, to tutorials and introductions on how to use the program. It’s available on iOS which is my favorite but also for OSX, and Linux I believe. Android is in the beta stages currently.
What is Cryptomator?
So cryptomator is a open sourced program, free for desktop versions and the Android beta, the iOS app is 5 dollars or something I can’t really remember, but what it does is solve a huge problem of tech giants like Google , even Apple from viewing what your uploading to cloud storage. What it does it’s encrypt these files device side, prior to uploading. Every File. So there is zero “Trust” involved. The code is of course present on Github for the tech savy community to examine and contribute to