Inferno - An extremely fast React-like javascript library for building modern user interfaces.
Deku - Functional view library for building UI components as an alternative to React
w2ui - W2UI is a small JavaScript UI library with a complete set of widgets: layout, grid, sidebar, toolbar, tabs, fields, popup, utilities.
Riot.js - Riot allows teams to communicate across a wide range of collaboration apps.
Preact.js - Preact is a fast 3kB alternative to React with the same modern API. Components & Virtual DOM.
Webix UI - An enterprise JavaScript Library for cross-platform app development with HTML5 JavaScript widgets and easy integration with most popular JavaScript Frameworks.