w2ui - W2UI is a small JavaScript UI library with a complete set of widgets: layout, grid, sidebar, toolbar, tabs, fields, popup, utilities.
Deku - Functional view library for building UI components as an alternative to React
Svelte - Cybernetically enhanced web 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.
Glimmer - Fast and light-weight UI components for the web