Zulip : Powerful slack-like open source group chat
BlurHash : BlurHash is a compact representation of a placeholder for an image.
Kanboard : Kanboard is a free and open source Kanban project management software.
Buildbot : Buildbot is an open-source framework for automating software build, test, and release processes.
Code Triage : Sign up to receive a different open issue in your inbox every day from your favorite GitHub repos
CryptoZombies is a free, open source, interactive code school that teaches you to build games on Ethereum. The course is designed for beginners to Solidity and starts off with the absolute basics.