Cachet : Beautiful & simple service statuses. The open source status page system, for everyone.
GetSimple CMS : GetSimple is an XML based, stand-a-alone, fully independant and lite Content Management System.
Zulip : Powerful slack-like open source group chat
Matrix : Matrix is an open standard for decentralised communication, providing simple HTTP APIs and open source reference implementations for securely distribu...
Pure Data (PD) : Pure Data (aka Pd) is an open source visual programming language. Pd enables musicians, visual artists, performers, researchers, and developers to cre...
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.