Discreete OS

The name says a lot about why she's on this list. To begin with, this is an operating system for work only. This means that you won't be able to install it even if you want to. It needs to be run directly from the source code (USB/disk). Like TAILS, every time you reboot, all data and activity logs are permanently deleted.

In fact, it is even equipped with anti-forensics features. Even the feds or other similar organizations will not be able to “recover” your data or actions after you shut down the system.  

Then it is not only open source, but also run by volunteers. This means that there is no “profit" in it. Of course, anyone who owns the code can verify all its claims.

All data stored in Discreet OS is stored in an encrypted “cryptobox". It can only be accessed under privacy protection, which means that even if your system is infected, your data remains safe.

Similarly, it is disconnected even from the Internet! You heard right — complete isolation.

Finally, the user interface has been designed to provide reliable protection for even the newest computer users. Yes, it's simple.