Flinto - The prototyping tool designers have been waiting for.
QUnit - What is QUnit? QUnit is a powerful, easy-to-use JavaScript unit testing framework. It's used by the jQuery, jQuery UI and jQuery Mobile projects and is capable of testing any generic JavaScript code, including itself!
Base UI Sketch Framework - Huge set of everything you need to design and prototype
Ava - Making conversations accessible for the deaf
Glyphy - Copy & paste fancy fonts + cool symbols ☞✺✐™
Chai - Chai is a BDD / TDD assertion library for node and the browser that can be delightfully paired with any javascript testing framework.