As per usual, and due to its huge popularity, we purposely didn’t include any jQuery-related resources in this post. jQuery needs and deserves its own post, so you should check out last monthsif that is what you are looking for.
Responsive Grid System
The Responsive Grid System is a fluid grid CSS framework for fast, intuitive development of responsive websites. Available in 12, 16 and 24 columns with media queries for all standard devices, clearfix, and optional reset.
Responsive Grid System →
Box CSS is a framework based on box-sizing: border-box and display:inline-block building principles.
Foldy960 is a responsive 960 grid, basically a little kit and some extra classes to get you going on making your 960.gs design responsive.
With Css2Less you can quickly convert your old CSS files to fresh new LESS files. As easy as copy/paste.
Responsive IE6 is a small tool to test your media queries on Internet Explorer 6.
Responsive IE6 →
Dirty Markup is a web-based tool to tidy and beautify your HTML, CSS & JS code. It combines the power of HTML Tidy, CSS Tidy, JS Beautify, and the Ace editor to effortlessly clean up your messy code.
SnipSave lets you save snippets of code online for future reference. It features a very easy-to-use interface where you can quickly create, edit and delete code snippets.
RWD Calculator is a simple calculator to help turn your PSD web template into the start of your responsive website. In other words, it turns pixels into percentages.
RWD Calculator →
The Responsinator helps web designers quickly get an indication of how their responsive site will look on the most popular mobile devices.
Timeline, as its name suggest, lets you create beautiful timelines that are easy and intuitive to use. It can pull media from different sources, with built in support for Twitter, YouTube, Flickr, Vimeo, Google Maps and SoundCloud.
CSSO is a CSS optimizer – more specifically, a CSS minimizer. Use it to improve and streamline your CSS.
Graphene is a realtime dashboard & graphing toolkit based on D3 and Backbone. It offers a very aesthetic realtime dashboard that lives on top of Graphite (but could be tailored to any back end).
By interpreting your semantic HTML5 tags, Fixie will automagically add the right type of content in the right places. Headings, paragraphs, links, images, sections…
Foresight.js gives webpages the ability to tell if the user’s device is capable of viewing high-resolution images (such as the 3rd generation iPad) before the image has been requested from the server.
Webshims lib is a modular capability-based polyfill-loading library, which focuses on accurate implementations of stable HTML5 features.
Kartograph is a lightweight framework for building beautiful, interactive vector map applications without Google Maps or any other mapping service.
Instead of being a chore, creating a new project and performing repetitive but necessary tasks such as linting, unit testing, concatenating and minifying files become trivially easy with Grunt.
jPages is a client-side pagination plugin that gives you a lot more features comparing to most of the other similiar plugins, such as auto page turn, key and scroll browse and showing items with delay.
dgrid is a lightweight, modular, and easily extensible grid component that takes full advantage of modern browsers and object stores.
SpritePad is a web-based tool that lets you create your CSS sprites within minutes. Simply drag & drop your images and have them immediately available as a PNG sprite + CSS code.
Keymaster is a simple micro-library for defining and dispatching keyboard shortcuts.
stroll.js is a collection of CSS list scroll effects. The style of scroll effect is determined via the class that is set on the list.
Skrollr allows you to animate any CSS property of any element depending on the horizontal scrollbar position.
Style Tiles are a design deliverable (in PSD format) consisting of fonts, colors and interface elements that help you communicate a web products visual brand.
Cutter.js truncates HTML code to limit its length.
Socialite provides a very easy way to implement and activate a plethora of social sharing buttons — any time you wish. On document load, on article hover, on any event!
Morris.js is a lightweight library that uses jQuery and Raphaël to make drawing time-series graphs easy.
dynamo.js gives offers a simple method to generate dynamic bits of HTML and add subtle effects to your content.
Intype is a fast and easy text editor. It has smart select & edit, snippet insertion and management, auto-paired characters, fast syntax highlighting and code-coloring themes.
Chico UI is a free and open source collection of easy-to-use web tools for developers and designers. Built on top of jQuery, these tools brings known interaction patterns for your website taking advantage of HTML5 and CSS3 features.
Chico UI →
The HTML5 Web Notifications come in two flavors: plain text and HTML. Plain text allows you to customize a couple of parameters, HTML shows any .html file you want as a notification.
Retina.js is an open-source script that makes it easy to serve high-resolution images to devices with retina displays.
jq-idealforms is a small framework to create awesome responsive forms. It’s been built on top of jQuery and LESS.
Spiffing allows you to write your CSS and stylesheets in conformance to proper British English (also known as correct English) grammar and spelling regulations.