Openfire

Imagine all your team communication in one place, instantly searchable, available wherever you go. That’s Slack. All your messages. All your files. And everything from Twitter, Dropbox, Google Docs, Asana, Trello, GitHub and dozens of other services. All together.

See content and chat history anytime, including team chats with Skype that are visible to the whole team. Private group chats are available for smaller group conversations.

HipChat is a hosted private chat service for your company or team. Invite colleagues to share ideas and files in persistent group chat rooms. Get your team off AIM, Google Talk, and Skype — HipChat was built for business.

Users can send messages and exchange photos, videos, stickers, audio and files of any type. It provides instant messaging, simple, fast, secure and synced across all your devices.

Mattermost is modern communication from behind your firewall.

Rocket.Chat is a Web Chat Server, developed in JavaScript, using the Meteor fullstack framework. It is a great solution for communities and companies wanting to privately host their own chat service or for developers looking forward to build and evolve their own chat platforms.

Free chat rooms for your public repositories. A bit like IRC only smarter. Chats for private repositories as well as organisations.

Zulip is powerful, open source team chat that combines the immediacy of real-time chat with the productivity benefits of threaded conversations. Zulip allows busy managers and others in meetings all day to participate in their teams chats.

Whether in a 1:1 chat or a dedicated group workspace, collaborate with your team in an organized way. Share and discuss Docs, Sheets, and Slides all in one place.

Flowdock is a web-based team chat service that integrates with your tools to provide a window into your team's activities. With the team inbox, everyone on your team can stay up to date. Stay connected with Flowdock's iOS and Android apps.

Keybase is for anyone. Imagine a Slack for the whole world, except end-to-end encrypted across all your devices. Or a Team Dropbox where the server can't leak your files or be hacked.

Communicate, collaborate and connect across desktop and mobile, using familiar features such as groups, chat and video calls. Because anything is possible when people work together.

It is messaging for teams that focus. Designed from the ground up to make you more productive. Everything in Quill is a thread. Focus on a topic, make decisions, and stay in flow. Choose the conversations you care about and safely filter everything else, knowing that you’re not missing out.

It is an enterprise communication and collaboration platform. that enables text, photo, voice and video communication, workflow management and collaboration among team members and enterprises of various sizes.

Twist is a communication app for teams who believe there’s more to work than keeping up with group chat apps, created by the makers of Todoist.

Flock is a communication app for teams. Packed with tons of productivity features, Flock drives efficiency and boosts speed of execution.

It is a group-oriented messaging platform with an integrated suite of collaboration tools that is tailor-made for workplaces in Asia

The community platform for the future.

It is a group chat app for business. Secure messaging, video chat, task management and file sharing. Real-time communication and increase productivity for teams.

It is a business communication app that includes real-time messaging, task management and automation. You can share files and make audio or video calls, right from within your chat channels. it is loaded with features to keep teams productive and cohesive.

It is a free messaging application that combines chat & messaging services into one application.

It supports end to end encryption, groups, channels and sharing of files between users, also registration does not require a phone number.

Campfire is like instant messaging, but designed exclusively for groups. Share text, files, and code in real time. Save transcripts so you don’t forget.

Business and personal conversations secured with end‑to‑end encryption and protected by European privacy laws.

Let's Chat is a persistent messaging application that runs on Node.js and MongoDB. It's designed to be easily deployable and fits well with small, intimate teams. It's free (MIT licensed) and ships with killer features such as LDAP/Kerberos authentication, a REST-like API and XMPP support.

Bring all the right people together instantly with built-in voice and video meetings. Turn conversations into action with integrated collaboration tools. Find the space to focus so you can get to done faster.

Leave email behind and manage all conversations with your team, partners and clients in Fleep. If some of them are not Fleep users yet, they will receive all messages as normal emails.

Actor is a platform for instant messaging. Actor provides features like large group chats; unlimited history storage; send/receive documents, photo, and video; authentication with one time password for phone number/email or OAuth2; easy integrations with external services.

It empowers and protects your most important people with the information and tools they need. Its Direct & Group Messaging means you can reach anyone, anytime, without the need for email addresses or phone numbers.

It brings your team together in a single space where they can discuss feedback, solve problems and collaborate better.

A desktop chat client for group-centric services like Slack and Discord. It provides a traditional compact desktop interface designed for power users.

It is an app-centric cloud-based service that provides a complete collaboration suite for teams to create, meet, message, call, whiteboard, and share, regardless of whether they're together or apart; in one continuous workstream before, during, and after meetings.

It is a team communication tool that organizes team collaboration, chats, files, and even emails into a single location, for any size team, for FREE.

It is a live social chat app to stay connected with your friends, team and colleagues at work. It streamlines the conversation by removing all unnecessary buttons and dropping you straight into the conversation.

It is a free software web application, where users can initiate discussions and put up proposals. It is a simple, user-friendly online tool for collaborative decision-making. Loomio empowers organisations and communities to turn discussion into action, wherever people are.

Hall is group chat, IM and video chat for companies and teams. Available free for the web, desktop and mobile. FREE anytime, anywhere.

Friends is like Slack except P2P, offline friendly and open source. We transmit data over secure channels and authenticate messages. It's made by a group of open source developers who are motivated to make a public chat platform that is easy to use but isn't centrally controlled, and where data is owned by its users.

Inspired by the best and built for XMPP, Kaiwa is a beautiful web-based client for the only standardized chat protocol. Combined with Prosody, one of the best XMPP servers out there, Kaiwa provides an unparalleled XMPP experience, on par with well-known commercial alternatives.

It is a chatting web app that you can access from the browser or download. You can link it with Google Drive to upload large files and make your own servers with channels.

It is a client/server chat program that is perfect for sending messages and exchanging files within an office or company. It can work within a company network or over the Internet.

Talk with great founders in real time. Dig deeper into topics that will help you boost your startup. Discover secrets. Forget about chaotic & spammy group channels.

It is a unified collaboration and communication (UCC) tool for companies, educational institutions, associations and churches. Get a solution that completely organizes your communication and that of your team. Make a video or audio call to more than 100 people at the same time. It connects conventional phone calls, with audio or video calls via the internet on your smartphone or on your web browser. It is an all in one solution which comes with your company's branding.

Messenger is an open-source web application and it's a small alternative to Slack. Total.js messenger is powerful micro application for each company with open source-code.

It is a self-hosted web-based IRC client for the modern world. It is a progressive web app (PWA), and can be installed from any modern browser for a native-like experience without having a dedicated app.

As a communication tool, it offers everything from free voice call and video calls and group chats to subscription updates and easy sharing of Photos. Users can post their daily photos on the “Memories” to share moods with friends and family.

Sameroom bridges real-time communication systems. Share channels between Slack teams. Bridge a Skype or Hangouts group with a channel on Slack. Connect a team on Slack with a team on HipChat, Gitter. Manage all your customer support queries as a team, from Slack. Respond to Intercom, Twitter, or Skype customer support questions from your team chat.

It is a click-to-talk collaboration tool with NLP-powered transcription, screen sharing, multiplayer app collaboration, crystal clear voice and video channels, file sharing, and more.

It covers all of your organizational needs through a single platform - no need to deploy 5 different tools simultaneously.

It is a secure peer-to-peer messaging app that works with or without internet access, cellular data or trust in the network. It is designed to be used as an everyday messaging application.

It is a powerful notification infrastructure that streamlines your product notifications with an API-first approach. Create and deliver transactional, crons, and engagement notifications on multiple channels with a single notification API.