GraphicsJS is a free and open-source JavaScript library for easily drawing absolutely anything including interactive and significantly more powerful in terms of out-of-the-box features than Raphael, Bonsai, and other existing SVG/VML based components.

Key features of GraphicsJS library making it stand out:
- Rich line drawing - not only Bezier curves, but also any deformations including arcs and other curves.
- Powerful text features - multiline texts, text measurement, including width, height, as well as wrap, overflow, indent, spacing, align, etc.
- Virtual DOM, designed for drawing rapidly and only what is necessary.
- Smart layering system including z-index.
- Its own transformation engine, with no need to use embarrassing in-browser transformations.
- Cross-browser support including legacy browsers (IE6+).
- Convenient JavaScript API, concise and with chaining support.

MarkupKit is an open-source framework for simplifying development of native iOS applications. It allows developers to construct user interfaces declaratively using a human-readable markup language, rather than visually using Interface Builder or programmatically in code.

Moment.js is an open source library to parse, validate, manipulate, and display dates in JavaScript.

Titon Toolkit is an open source project that provides an extensible front-end HTML, CSS, and JavaScript user interface components and behaviors for the responsive, mobile, and modern web.

Sugar is an open source Javascript library that extends native objects with helpful methods. It is designed to be intuitive, unobtrusive, and let you do more with less code.

Zepto is a minimalist JavaScript library for modern browsers with a largely jQuery-compatible API. If you use jQuery, you already know how to use Zepto. While 100% jQuery coverage is not a design goal, the APIs provided match their jQuery counterparts. The goal is to have a ~5-10k modular library that downloads and executes fast, with a familiar and versatile API, so you can concentrate on getting stuff done.

Mercury is a truly open source modular frontend framework.

Bootflat is an open source Flat UI KIT based on Bootstrap 3.1.1 CSS framework. It provides a faster, easier and less repetitive way for web developers or designers to create elegant web apps. It is compatible with the following browsers: IE8, IE9, IE10, IE11, Firefox, Safari, Opera, Chrome.

A set of controls and styles converting your WPF application into a great looking Modern UI app. This open source project is a spin-off of XAML Spy, the visual runtime inspector for Silverlight, Windows Phone, Windows Store and WPF. Read the announcement at xamlspy.com.

Visage is a domain specific language (DSL) designed for the express purpose of writing user interfaces. A Visage application models the user interface you are designing both in appearance and function.