I have been repeatedly disappointed with the popular end-to-end encrypted messaging apps controlled by large centralized organizations. For years I've been saying, that I need to write my own. Well I finally did write i2p-chat. It is a very simple code base, written in C++ and uses I2P cryptography. It's free open source code consisting of a small cli client and a server that runs as an I2P Hidden service. The client sends messages via the I2P SAM v3 api.
Messages are sent via the client as:
i2p-chat <nickname> <message_text>
nicknames are linked to I2P hidden service I2P destinations in a sqlite3 address book database.
You create your own nickname and link your i2p-chat-server I2P hidden service I2P destination. You tell those you wish to communicate with your nickname and your I2P hidden service I2P destination.
It is intended for private and secure text messaging.
If anyone is interested, they can find more info at: http://sovereign.i2p/i2p-chat.html