Preact.js - Preact is a fast 3kB alternative to React with the same modern API. Components & Virtual DOM.
Higher Logic - Private, secure online communities that stimulate conversation and ignite engagement.
Inferno - An extremely fast React-like javascript library for building modern user interfaces.
Tribe.so - Tribe is a white-label platform, empowering the new generation of online communities.
Glimmer - Fast and light-weight UI components for the web
Discourse - Discourse is an open source discussion platform built for the next decade of the Internet.