Modern XMPP ("Jabber") Chat Client using GTK/Vala
Desktop Telegram client with good customization and Ghost mode.
Telegram Desktop messaging app
A free and open source instant messaging and VoIP platform
Saves Discord chat logs to a file
The first messaging platform operating without user identifiers
Elegant Facebook Messenger desktop app
A Decentralized, Onion Routed, Private Messenger
A New Kind of Instant Messaging
Open source machine learning framework to automate text conversations
Desktop client for Facebook Messenger
Private messenger for Windows, Mac, and Linux
LXMF client for Android, Linux and macOS to communicate with people
WhatsApp library for NodeJS that connects through the browser app
A Tox-based instant messaging and video chat client
A reference implementation of the SimpleX Messaging Protocol
In-memory message queue with an Amazon SQS-compatible interface
Home to the Signal Protocol and other cryptographic primitives
Franz is a free messaging app for services like WhatsApp, Slack, etc,
Telegraph is a Laravel package for fluently interacting with Telegram
Python chatbot framework with Natural Language Understanding
A free (libre) open source, mobile OS for Ethereum
Distributed instant messaging system for developers
A universal instant messaging (IM) program
You can message and share files inside your intranet without a server.