Slack - A messaging app for teams who see through the Earth!
9mCollab - Collaborate (efficiently) Conclude (fast) Contribute (in the knowledge base)
Wipshot - Share with WIP and Review
Mattermost - Mattermost is an open source alternative to Slack.
Quip Chat Rooms - Real-time chat with your team
Loop Email - Emailing for teams: Organize your Inbox into channels 💌