Ratchet
Prototype iPhone apps with simple HTML, CSS, and JS components.
Local Forage
Offline storage, improved. Wraps IndexedDB, WebSQL, or localStorage using a simple but powerful API.
Svgo
SVGO is a Nodejs-based tool for optimizing SVG vector graphics files.
Summernote
Super simple WYSIWYG editor
Tether
A positioning engine to make overlays, tooltips and dropdowns better #hubspot-open-source
Mojs
motion graphics library for the web
Bootstrap Datetimepicker
Date/time picker widget based on twitter bootstrap
Angular Strap
AngularJS 1.2+ native directives for Bootstrap 3.
Parallax
Parallax Engine that reacts to the orientation of a smart device
Hover
A collection of CSS3 powered hover effects to be applied to links, buttons, logos, SVG, featured images and so on. Easily apply to your own elements, modify or just use for inspiration. Available in CSS, Sass, and LESS.
Html2canvas
Screenshots with JavaScript
Babylon.js
Babylon.js: a complete JavaScript framework for building 3D games with HTML 5 and WebGL
Impress.js
It's a presentation framework based on the power of CSS3 transforms and transitions in modern browsers and inspired by the idea behind prezi.com.
Backbone Marionette
Make your Backbone.js apps dance with a composite application architecture!
Plotly.js
The open source javascript graphing library that powers plotly
jQuery Pjax
pushState + ajax = pjax