What are some alternatives?
Slack - A messaging app for teams who see through the Earth!
Skype - Stay in touch with your family and friends for free on Skype. Download Skype today to chat and call on desktop and mobile.
WhatsApp - WhatsApp Messenger: More than 1 billion people in over 180 countries use WhatsApp to stay in touch with friends and family, anytime and anywhere.
Glip - Glip is fully searchable, real-time group chat & video chat, task management, file sharing and more, in one easy-to-use app. Get started FREE today.
Wire - Private & Secure Messenger
Mattermost - Mattermost is an open source alternative to Slack.