Free Slack Alternatives

A VoIP application and platform designed for creating communities and connecting gamers, and people rallying around specific causes. The Discord client is a free to use and can handle text, image, video and audio communication between users in a chat channel. Currently over 250 million users use the software to connect with others across the globe.

Mattermost is an open-source, self-hostable enterprise team collaboration and messaging application. The software can be deployed to on-premis or to cloud instances. Mattermost is designed for internal use within organizations and businesses in financial services, government, healthcare, remote work, and enterprise DevOps, where teams use Mattermost to power collaboration at every stage of the DevOps lifecycle.

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A free, unlimited and open-source chat software. Rocket.Chat have set out to be a replacement for email, HipChat & Slack and is provided as Software-as-a-Service (SaaS) or a self-hosted community edition. Rocket.Chat is feature packed and can be used for video conferencing, file sharing, voice messages and more. The software integrates with third-party services like GitHub, GitLab, JIRA, and Confluence and provides an API that can be used for authentication and integration across these services.

Matrix.org is an open network for secure, decentralized communication. It gives you a simple HTTP APIs and SDKs (iOS, Android, Web) to create chatrooms, direct chats and chat bots, complete with end-to-end encryption, file transfer, synchronised conversation history, formatted messages, read receipts and more. All conversations on Matrix are replicated over all the servers participating in them, meaning there are no single point of control or failure.

Jitsi is an open-source project and software toolset that allows you to easily build and deploy secure video conferencing solutions. At the heart of Jitsi are Jitsi Videobridge and Jitsi Meet, which let you have conferences on the internet, while other projects in the community enable other features such as audio, dial-in, recording, and simulcasting.  Jitsi supports popular protocols such as SIP, XMPP/Jabber, ICQ/AIM, Windows Live, Yahoo!, Google Hangouts, OTR, ZRTP and more.

With Google Hangouts, you can keep in touch with through chat, video or voice calls in person or as a group. Google Hangouts is a cross-platform messaging app developed by Google that is available for Android, Chrome OS, iOS, Google Chrome or any browser that is compatible with Google Chrome Extensions.

Threema is a messenger application that puts security and privacy first. The application is designed to generate as little user data as possible. The service is fully GDPR-compliant and the company has its own servers hosted in Switzerland. With Threema you can keep in touch with friends, family and co-workers while enjoying privacy and rest assured that you personal data is not commoditized.

Gitter is an open-source instant messaging and chat room system for developers designed to make community messaging, collaboration and discovery as smooth and simple as possible. Gitter is provided as software-as-a-service and integrates with GitLab and GitHub repositories to make discussion around code even easier. With Gitter, you can can easily create, organise and grow your communities, inviting others to join just in one click. Over 1.5M users across 100K communities use Gitter to discuss code and development progress.

Ripcord is a desktop chat client for group-centric services like Slack and Discord. It provides a traditional compact desktop interface designed for power users. It has a small resource footprint, responds quickly to input, and gets out of your way. With Ripcord, you can connect with friends, family and co-workers.

WhatsApp is free messenger app for chat and voice over IP, owned and managed by Facebook. The application allow users to send text and voice messages, make voice and video calls and share images, media files and user locations with friends and family.

Telegram X is a development version of the chat application Telegram. The goal of Telegram X is to reinvent Telegram and explore new frontiers in speed, ease of use, quality of animations, and all other aspects surrounding online communication. Telegram X is an experimental app that may or may not eventually replace the existing official Telegram, or simply used as a public beta test.