Usually I work, browse, email on a PC and not on a smartphone. However I use viber and I had it only on the phone. As there is a PC version, I thought I give it a try. On the download page there is of course the windows version, but there are also two packages for linux: one .deb for Ubuntu and .rpm for Fedora. I tried to install the .deb, but it has some dependencies on an older libssl. So what I did, I just unpacked it with
dpkg -x viber.deb out/
and then manually moved to /opt. When trying to start I got some error message that I could not interpret, but using strace to figure out, what was going on, I saw that some libraries were missing. Installing them solved the issue:
apt-get install libxcb-icccm4 libxcb-image0 libxcb-keysyms1 libxcb-randr0 libxcb-render-util0 libxcb-xkb1 libxkbcommon-x11-0
Now it runs, and seems to be working.