Conversations
Conversations is a messaging app for instant messaging, sharing photos and other files, as well as group chats. It is a paid app, and it is open-source, Jabber/XMPP client for Android 5.0+ smartphones. The communication between Conversations and the XMPP server as well as the communication between the individual servers is TLS encrypted. Conversations also has the choice to enable one of two end-to-end encryption mechanisms (OMEMO or OpenPGP).