qiscus!

Mattermost is an open source, self-hosted Slack alternative.

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

HipChat is an instant messaging service designed for companies and teams. It has persistent chat rooms, one-to-one chat, searchable chat history, file sharing via drag & drop and clipboard, inline image previews, an API, chat over SMS, and more.

Self-hosted chat for small teams.

hack.chat is a minimal, distraction-free chat application.Channels are created and joined by going to https://hack.chat/?your-channel . There are no channel lists, so a secret channel name can be used for private discussions.

dialog app is built and designed for corporate communication on all types of mobile devices - tablet, mobile phones etc.

Campfire is a simple web-based real-time group chat tool for business. It makes real-time communication with 2-60 people as simple as visiting a web page.

TribeScale is a startup that aims to enhance teamwork in companies through the improvement of communication, coordination, and the pace on the basis of targets set. It is designed by taking as a reference the methodologies of the most innovative teams in the world: (Apple, Tesla, Google, Virgin...).Companies that use TribeScale have said that it has ended with 80 percent of working meetings. We are a platform for communication and management of teams very advanced and action-oriented, with functionalities such as creating and assigning tasks, sending surveys, decision-making, and automation of processes. »

Ryver provides all of your team communications in one place: chats, posts, and files. Invite as many team members and guests as you need.

Fleep is a messenger for your teams and projects. It enables communication within and across organizations - be it your team chats, project communication or 1:1 conversations.