Dino is a modern IM client using XMPP (Jabber) with support for both OpenPGP and OMEMO. It looks very nice and can already be used for chatting and group conversations. It is, however, not yet stable nor feature-complete. If you are looking for something like Conversations (Android XMPP client), but for the desktop, Dino is for you. If you like to have something more stable and feature-complete, try Gajim instead. I use both! :~)
Dino is written in C and Vala, uses the GTK+ UI toolkit and looks best in Gnome, XFCE, or other GTK+ based desktops. I heard about planned versions for Windows and MacOS, too, but don't hold your breath.
How to install Dino on Debian?
Since yesterday, the Dino IM client is available in the official Debian repositories, but so far only in the "experimental" distribution. To install it, Debian users have to:
$ echo deb [url=https://deb.debian.org/debian/]https://deb.debian.org/debian/[/url] experimental main | sudo tee /etc/apt/sources.list.d/experimental.list
$ sudo apt update
$ sudo apt -t experimental install dino-im
This should work on nine official and five unofficial architectures for at least unstable and testing. Not sure about stable. I'm pretty sure, that oldstable will not work.
Why the "-im" suffix for Dino in Debian?
There used to be another program, an "integrated MIDI piano roll editor and sequencer engine", by the same name in Debian. Many references to the old program still exist, so it would be problematic to recycle the name for a different purpose.