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.

RemoteTeam - Remoteteam.com helps remote teams become great places to work with the fully-integrated platform to automates payments and HR tasks.

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

Swipes - Plan projects, take action and discuss.

Flow - Stop managing projects from your inbox.

ApproveIt for Slack - Get approvals in minutes, not days. Right from Slack!