ZNC is an IRC network bouncer or BNC. It can detach the client from the actual IRC server, and also from selected channels. Multiple clients from different locations can connect to a single ZNC account simultaneously and therefore appear under the same nickname on IRC.

jj is a simple file-system-based Jabber client, inspired by ii IRC client. Interaction with jj is done by writing and reading files from the server directory which jj creates. It is perfect for bots and notifications.

Purple-Mattermost is a plug-in for Purple, the instant messaging library used by Pidgin and Bitlbee, among others, to access Mattermost servers.

This module implements XEP-0363: it allows clients to upload files over HTTP.

Toxic is a console-based instant messaging client, using c-toxcore and ncurses. It provides audio calls, sound and desktop notifications, and Python scripting support.

This package provides Zulip's Flask server for running bots.

libqmatrixclient is a Qt library to write clients for the Matrix instant messaging protocol. Quaternion is the reference client implementation. Quaternion and libqmatrixclient together form the QMatrixClient project.

This package provides Zulip's Bot framework.

Python-nbxmpp is a Python library that provides a way for Python applications to use the XMPP network. This library was initially a fork of xmpppy.

SILC (Secure Internet Live Conferencing) is a modern and secure conferencing protocol. It provides all the common conferencing services like private messages, instant messages, channels and groups, and video and audio conferencing.

This module implements support for a Encrypted Push Notifications, a custom extension to XEP-0357: Push Notifications.

MQTT and MQTT-SN are lightweight publish/subscribe messaging transports for TCP/IP and connection-less protocols (such as UDP). The Eclipse Paho project provides client side implementations of MQTT and MQTT-SN in a variety of programming languages. This package is for the Python implementation of an MQTT version client class.

pn provides a command line tool that allows users to operate on phone numbers (get validity information, reformat them, or extract numbers from a text snippet), using libphonenumber.

Libstrophe is a minimal XMPP library written in C. It has almost no external dependencies, only an XML parsing library (expat or libxml are both supported).

GNT is an ncurses toolkit for creating text-mode graphical user interfaces in a fast and easy way. It is based on GLib and ncurses.

GNU Freetalk is a command-line Jabber/XMPP chat client. It notably uses the Readline library to handle input, so it features convenient navigation of text as well as tab-completion of buddy names, commands and English words. It is also scriptable and extensible via Guile.

mtxclient is a C++ library that implements client API for the Matrix protocol. It is built on to of Boost.Asio.

Chatty is a chat program for XMPP and SMS. It works on mobile as well as on desktop platforms. It's based on libpurple and ModemManager.

mod_invites_api provides an authenticated HTTP API to create invites using mod_invites.

You can use the command-line to create and manage API keys.

HexChat lets you connect to multiple IRC networks at once. The main window shows the list of currently connected networks and their channels, the current conversation and the list of users. It uses colors to differentiate between users and to highlight messages. It checks spelling using available dictionaries. HexChat can be extended with multiple addons.

libsignal-protocol-c is an implementation of a ratcheting forward secrecy protocol that works in synchronous and asynchronous messaging environments. It can be used with messaging software to provide end-to-end encryption.

Loudmouth is a lightweight and easy-to-use C library for programming with the XMPP (formerly known as Jabber) protocol. It is designed to be easy to get started with and yet extensible to let you do anything the XMPP protocol allows.

This is a client library for libsignal-protocol-c. It implements the necessary interfaces using libgcrypt and sqlite.

This module implements XEP-0357: Push Notifications.

Some platforms, notably Apple’s iOS and many versions of Android, impose limits that prevent applications from running or accessing the network in the background. This makes it difficult or impossible for an XMPP application to remain reliably connected to a server to receive messages.

In order for messaging and other apps to receive notifications, the OS vendors run proprietary servers that their OS maintains a permanent connection to in the background. Then they provide APIs to application developers that allow sending notifications to specific devices via those servers.

When you connect to your server with a client that requires push notifications, it will use this module to set up a “push registration”. When you receive a message but your device is not connected to the server, this module will generate a notification and send it to the push gateway operated by your application’s developers). Their gateway will then connect to your device’s OS vendor and ask them to forward the notification to your device. When your device receives the notification, it will display it or wake up the app so it can connect to XMPP and receive any pending messages.