Balloon.css
Simple tooltips made of pure CSS
Heatmap.js
JavaScript Library for HTML5 canvas based heatmaps
Bootstrap Tour
Quick and easy product tours with Twitter Bootstrap Popovers
Flex Slider
An awesome, fully responsive jQuery slider plugin
Colorbox
A light-weight, customizable lightbox plugin for jQuery
Graphql Editor
GraphQL Visual Node Editor
jQuery.nicescroll
nicescroll plugin for jquery - scrollbars like iphone/ipad
Datamaps
Maps for interactive data visualizations in Javascript
Odometer
Smoothly transitions numbers with ease. #hubspot-open-source
Tonal
A functional music theory library for Javascript
Prosemirror
The ProseMirror WYSIWYM editor
Holder
Holder renders image placeholders entirely on the client side.
Zip.js
JavaScript library to zip and unzip files
Ractive
Next-generation DOM manipulation
Open Jscad.org
OpenSCAD + JavaScript = OpenJSCAD, edit locally or remote online, preview in browser direct via WebGL.
Imba
The new programming language for web apps
Intercooler Js
Making AJAX as easy as anchor tags