These builds are for testing purposes only.

Quickly and easily find out how long you have been on twitter, and compare it to others. Sign in with twitter to begin.

The responsinator is designed to test responsive websites on different device resolutions.

find that tricky breakpoint.
Enter the url to your site - local or online: both work - and use the controls to adjust the width and height of your viewport to find exact breakpoint widths in pixels. Then use that information in your media queries to create a responsive design.

dabblet is an interactive playground for quickly testing snippets of CSS and HTML code.

Exactly how much CSS3 does your browser support?

An interface to test out CSS 3D transforms.

Acid3 Browser Test

Acid3 is the third in a series of test pages written to help browser vendors ensure proper support for web standards in their products.

Acid3 is primarily testing specifications for “Web 2.0″ dynamic Web applications. Also there are some visual rendering tests, including webfonts. Here is the list of specifications tested:

• DOM2 Core
• DOM2 Events
• DOM2 HTML
• DOM2 Range
• DOM2 Style (getComputedStyle, …)
• DOM2 Traversal (NodeIterator, TreeWalker)
• DOM2 Views (defaultView)
• ECMAScript
• HTML4 (<object>, <iframe>, …)
• HTTP (Content-Type, 404, …)
• Media Queries
• Selectors (:lang, :nth-child(), combinators, dynamic changes, …)
• XHTML 1.0
• CSS2 (@font-face)
• CSS2.1 (‘inline-block’, ‘pre-wrap’, parsing…)
• CSS3 Color (rgba(), hsla(), …)
• CSS3 UI (‘cursor’)
• data: URIs
• SVG (SVG Animation, SVG Fonts, …)

The IMDb video panorama demonstrates the use of standard HTML mark-up that works across all browsers. In this demo you'll find that the individual videos scroll smoothly when panning to the left or right. Upon selecting a video, the movie title at the top with sub-pixel accuracy animates smoothly, while the bottom metadata fades and flies into place. This is all done without missing too much of a beat in IE9 maintaining a fairly high framerate.