About The W3C mobileOK Checker

Table of contents

  1. About this service
  2. References and other resources
  3. Credits

About this service

The W3C mobileOK Checker is a free service by W3C that helps check the level of mobile-friendliness of Web documents, and in particular assert whether a Web document is mobileOK.

To understand why checking a Web document for mobile-friendliness really matters, it is probably worth emphasizing a few points about the so-called mobile world. Compared to a regular desktop computer, a mobile device may be regarded as limited at first glance: smaller screen size, smaller processing powers, smaller amount of memory, no mouse, and so on. Compared to fixed data connections, mobile networks can be slow and often have a higher latency. Compared to a user sitting in front of his computer, the user on the go has limited time and is easily distracted. On top of these constraints, the mobile world is highly fragmented: many different devices, each of them defining a unique set of supported features.

For these reasons, although most mobile devices may render Web documents, the user experience when browsing the Web on a mobile device is often poor when a Web document hasn't been designed with mobility in mind.

To help ensure that an appropriate user experience is possible on as many mobile devices as possible, the Mobile Web Best Practices Working Group, part of the W3C Mobile Web Initiative, defined a set of recommended guidelines to follow when creating Web documents: the Mobile Web Best Practices 1.0 specification.

Out of these best practices, the working group extracted a consistent set of best practices that may be automatically checked. This set of best practices defines the notion of mobile-friendliness mentioned above, and this is what the W3C mobileOK Checker actually tests. When a Web document passes all the tests, it is mobileOK. More precisely, the tests run by the W3C mobileOK Checker are formally defined in the mobileOK Basic Tests 1.0 specification.

Being mobileOK is neither a guarantee that the Web document may be rendered correctly by all mobile devices, nor an insurance that the user experience was correctly addressed. Further quality improvements based on the full set of the Mobile Web Best Practices may be in order. The Mobile Web Best Practices Flipcards are a useful and handy companion for creators of Web content to keep the Mobile Web Best Practices in mind.

References and other resources

Documentation & Specifications

Relevant activities

Online Tools & Other Validators

In addition to this checker, the W3C is offering a number of other tools to help you check various types of documents (HTML, XHTML, CSS, RDF, P3P, ...), find broken links in your Web pages, and so on. All these tools are listed on the W3C's QA Toolbox.

The W3C also hosts a number of other Open Source software projects.


The W3C mobileOK Checker is based on an open source Java library developed within the Mobile Web Best Practices Working Group by the Checker Task Force.

The user interface of the W3C mobileOK Checker was created and is maintained by W3C staff. Olivier Thereaux helped design the look & feel of the pages. Dominique Hazaël-Massieux and François Daoust focus on the structure of the report and the clarity of the messages.