Apps with 'OMEMO' feature

Conversations is a privacy focused, open source XMPP Texting [Jabber] client for Android 4.0+ smart phones with wife-approved easy encryption [OTR, OMEMO, or GPG].

Dino is a modern open-source chat client for the desktop. It focuses on providing a clean and reliable Jabber/XMPP experience while having your privacy in mind. Using GTK+/Vala.

The goal of Gajim is to provide a full featured and easy to use XMPP client. Gajim works nicely with GNOME, but does not require it to run. It is released under the GNU General Public License.

A spin-off of the popular Jabber/XMPP client Conversations with automatic contact discovery.

Monal is an open source iOS and macOS XMPP Chat-Client. It can connect to any standard XMPP chat server such as Gtalk or Facebook chat.

An encrypted instant messaging with video call and GPS features for android.

Open Source Android XMPP Client.