Ripcord - A desktop chat client for Discord and Slack

Duolingo - Duolingo is a free language learning app for iOS, Windows and Android devices. The app makes learning a new language fun by breaking learning into small lessons where you can earn points and move up through the levels. Read more about Duolingo.

Crugo - Crugo is a simple group collaboration platform for your team

Eduflow - Digital learning that actually teaches students something

Spectrum Chat - A newly open sourced self hosted Slack like alternative for building persistent chat communities

Backchannel Chat - Backchannel Chat is best in class discussion tool that is intended for teachers to streamline their class activities.