Web Compatibility Test for Mobile Browsers

The Web Compatibility Test for Mobile Browsers combines in a single page a number of Web technologies that we believe are the foundation for a better Web experience, especially on mobile devices.

Using a very visual scheme of a set of squares whose color depend on the proper implementation of a given technology, it helps assess at a glance where a given browser might be lacking to support this improved Web experience.

Accessing it

The test is available at:

You can also check how the test has evolved through the CVS module view.

Tested Technologies

The squares are roughly sorted by order of difficulty: the first row tests "baseline" technologies, the second row corresponds to technologies that are already widely used today, and the third row tests for support of technologies that we believe will be important in the near future.

State and history of technologies tested in the Web Compatibility Test

Map of the included tests

The following technologies are tested as of today:

1. CSS2 min-width

Fluid page widths, defined in percent of the screen width, often depend on the min-width and max-width properties to avoid turning unreadable on small screens. The former property is tested here.

2. Transparent PNG

PNG, a bitmap image format, supports transparency and alpha channels, that are useful in building appealing visual effects

3. GZIP support

The HTTP protocol allows data to be sent gzip-compressed when the client advertises its capability to uncompress them (through the Accept-Encoding header), thus saving bandwidth.


The HTTPS protocol is used to establish secure and encrypted connections on the Web.

5. Cookies support

Tests if the UA supports HTTP cookies (through Javascript).

6. iframe inclusing of XHTML-served-as-XML content

Tests if the UA supports XML content-types by loading an XHTML document with the content-type application/xhtml+xml.

7. XMLHTTPRequest

XMLHTTPRequest is at the core of AJAX, allowing to update a subset of an HTML page without requesting a new full content transfer

8. Static SVG (gzipped)

SVG allows authors to define vector-based graphics, that can be scaled up and down, fitting well the needs of mobile devices. Serving it gzip-ed allows to reduce the data sent through the network.

9. CSS Media Queries

CSS Media Queries allow authors to constrain CSS rules to specific contexts, for instance so that they only apply to screens of a given maximum width. The min-width feature is tested here.

10. JavaScript framework

This test checks support for loading and applying one of the popular JavaScript framework - in this case, JQuery. These frameworks are an increasingly important part of the Web experience.

11. Dynamic SVG

SVG also supports animations, that can be used to create appealing interfaces

12. IRIs and IDN

IRI (Internationalized Resource Identifiers) allows to write Web addresses with any character of any language and script in the world; IDNs (Internationalized Domain Names) ensures that the DNS resolution works also on non-ASCII domain names.

13. DOM 'mutation' events

The Document Object Model allows Web developers to trigger and notice browser-based events (e.g. a mouse click); Mutation events are triggered when a piece of a Web page is modified (e.g. by a script); they are particularly interesting on devices with small screens, where the user might not notice that a change occurred in a non-visible part of the page.

14. The canvas element

The canvas element defined in HTML5 offers a Javascript graphics API

15. contenteditable

The contenteditable attribute makes rich text editing of any element possible. Support for this attribute is tested.

16. CSS3 selectors

CSS3 introduces a number of new selectors, allowing more fine-grained styling, leading to better layouts. The nth-child() selector is tested here.

Dominique Hazaël-Massieux

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