iMessage is an instant messaging service.

Bitmessage is a decentralized, encrypted, peer-to-peer, trustless communications protocol that can be used by one person to send encrypted messages to another…

Digsby provides you with IM, email and Social networks in one easy to use application.

Empathy is an instant messaging (IM) and voice over IP (VoIP) client which supports text, voice, video, file transfers, and inter-application communication ov…

Gajim is an instant messaging client for the XMPP protocol which uses the GTK+ toolkit.

ICQ is an open source instant messaging software.

Bit Chat is a secure, peer-to-peer, open source instant messenger with end-to-end encryption.

Coccinella is a free and open-source cross-platform client for the XMPP/Jabber-instant messaging-protocol.

Disa is your new messaging hub. Conversations from different services can seamlessly be joined together, or disbanded within seconds.

Facebook Messenger is the official Facebook app that lets you have text conversations with all of your friends on the popular social network.

HexChat is an open-source, cross-platform IRC client.

IM+ supports simultaneously major IM services, including Google Talk, Twitter DMs, Yahoo!, AIM/iChat, ICQ, Jabber (and Slack through Jabber), etc.