Public - Group chats.
Sharetribe - Build your online marketplace business. You don't need a developer.
Chalk - Chalk is a calculator that tries to do right what others do wrong.
Cocorico - Cocorico is a state-of-the art Open Source solution to create an Airbnb or Blablacar for anything.
SoChat - Chat with everyone
MarketplaceKit - MarketplaceKit is a platform for building different types of online marketplaces.