Browser Sync
Keep multiple browsers & devices in sync when building websites. http://browsersync.io
Meteor
Meteor, an ultra-simple, database-everywhere, data-on-the-wire, pure-Javascript web framework.
Validate.js
Lightweight JavaScript form validation library inspired by CodeIgniter.
Remarkable
Markdown parser, done right. Commonmark support, extensions, syntax plugins, high speed - all in one.
Csscomb.js
CSS coding style formatter
Dygraphs
Interactive visualizations of time series using JavaScript and the HTML canvas tag. The dygraphs JavaScript library produces interactive, zoomable charts of time series.
Code Mirror
In-browser code editor
Foundation
The most advanced responsive front-end framework in the world. Quickly create prototypes and production code for sites and apps that work on any kind of device.
Responsive Elements
Responsive elements makes it possible for any element to adapt and respond to the area they occupy. It's a tiny javascript library that you can drop into your projects today.
Grid
Drag and drop library for two-dimensional, resizable and responsive lists
Bootstrap Daterangepicker
Date range picker component for Bootstrap
Winjs
WinJS project by Microsoft Open Technologies
Ratchet
Prototype iPhone apps with simple HTML, CSS, and JS components.
Limejs
HTML5 game framework for web and iOS
Jquery Timeago
Timeago is a jQuery plugin that makes it easy to support automatically updating fuzzy timestamps (e.g. "4 minutes ago").
Elevator.js
Finally, a "back to top" button that behaves like a real elevator.
Crossfilter
Fast n-dimensional filtering and grouping of records.