Telegram Desktop messaging app
A free (libre) open source, mobile OS for Ethereum
Home to the Signal Protocol and other cryptographic primitives
A New Kind of Instant Messaging
A Decentralized, Onion Routed, Private Messenger
Private messenger for Windows, Mac, and Linux
LXMF client for Android, Linux and macOS to communicate with people
Modern XMPP ("Jabber") Chat Client using GTK/Vala
You can message and share files inside your intranet without a server.
Chat Messenger. E-Mail-Client. Websearch. Filetransfer.
minimalistic, secure and autonomous P2P messenger
A P2P Messenger which uses JXTA. It provides secure RSA/AES end-to-end
Underground IM is a free Java Instant Messaging solution.