Zulip - Chat for distributed teams. Zulip combines the immediacy of real-time chat with an email threading model. With Zulip, you can catch up on important conversations while ignoring irrelevant ones.

Zoom - Equip your team with tools designed to collaborate, connect, and engage with teammates and customers, no matter where you’re located, all in one platform.

Kwayet - Team chat & collaboration app, a simple way to Slack

Butter - Butter is a newly launched chatting application that focuses more on the privacy of its users.

Flow - Stop managing projects from your inbox.

Habit List - Create good habits and break bad ones with the app that keeps you focused.