Wee

Wee is a front-end framework for developing responsive websites using a mobile-first CSS bootstrap paired with a powerful JavaScript library.
Flat UI Pro

Flat UI Pro is Twitter Bootstrap Design Framework that includes HTML and PSD versions. Flat UI Pro contains a huge number of basic components, themes, icons and glyphs.
Fluid

Turn Your Favorite Web Apps into Real Mac Apps.
Kube Web Framework

Free CSS/JS advanced and flexible framework.
DevExtreme

HTML5 Widgets & SPA Framework for Desktop and Mobile.
Fig

Fast, isolated development environments using Docker.
Proton Native

A React environment for cross platform native desktop app.
Gridlex

Simple. Robust. Responsive. Flexible.
TouchstoneJS

React.js powered UI framework for
developing beautiful hybrid mobile apps.
Standard Widget Toolkit

The Eclipse Foundation – home to a global community, the Eclipse IDE, Jakarta EE and over 350 open source projects, including runtimes, tools and frameworks.