Top Alternatives to Rocket.Chat

Skype is an instant messaging and VOIP (Voice Over Internet Protocol) client to communicate with people in a distant place.

Slack is a cloud-based team collaboration tool.

Glip is fully searchable, real-time group chat; video chat, task management, file sharing app.

Mattermost is an open source, private cloud Slack-alternative, Workplace messaging for web, PCs and phones. MIT-licensed.

Matrix is an open protocol for real-time communication. It is designed to allow users with accounts at one communications service provider to communicate with users of a different service provider via online chat, Voice over IP, and Videotelephony.

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.

Whaller allows teams and organizations to create their own internal social networks, meaning no adverts and no data exploitation.

Hibox provides task management, business chat and video calls.

TribeScale is an All-in-One platform to coordinate your team around what really matters - communication, goals, decisions, tasks and results.

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

Jitsi Meet is an open-source (Apache) WebRTC JavaScript application that uses Jitsi Videobridge to provide high quality, scalable video conferences.

Zulip is a chat and collaborative software.

Dialog Messenger is a handy and feature-rich enterprise multi-device messenger available for server or cloud.

Cisco WebEx provides on-demand collaboration, online meeting, web conferencing and video conferencing applications.

YakYak is a desktop chat client for Google Hangouts.