chat-servers

Kerio Connect makes email, calendars, contacts and task management easy and affordable. With Kerio Connect, you have immediate, secure access to your communications anytime, anywhere, on any device - without complexity or expensive overhead.

Exchange business-class email helps increase user productivity while protecting your data. Get it as a hosted service or run it on your servers.

Openfire (formerly Wildfire) is a cross-platform instant messaging (IM) and groupchat server. It uses the only widely adopted open protocol for instant messaging, XMPP (also called Jabber). Openfire is incredibly easy to setup and administer, but offers rock-solid security and...

Rocket.Chat is a Web Chat Server, developed in JavaScript, using the Meteor fullstack framework.

Fully open source instant messaging server and clients. No proprietary components or non-free dependencies. Backend in pure Go (GPL 3.0), with a command-line administration tool in python + gRPC. Clients for Android, iPhone, and Web - ReactJS (all licensed under Apache 2.0).

Zulip is the only modern team chat app that is designed for both live and asynchronous conversations. Zulip topics create a separate space for each discussion, so different conversations will never get in each other's way.