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[Draft] Selecting Web Accessibility Assessment Tools

Note: This document is a draft [see change log in progress] and should not be referenced or quoted under any circumstances. This document is under development by the Education and Outreach Working Group (EOWG), and will be offered to other W3C groups and the public for review.

1. Introduction

Web accessibility assessment tools can be used to investigate the accessibility of a Web site and to implement accessibility features. There are several types of assessment tools which provide different features and characteristics. Many different requirements may play a role when selecting suitable assessment tools. The nature of the Web site and the organization developing it may be most significant factors. Sometimes, a single tool may be adequately able to address the requirements of the developers. For some organizations, it may be suitable to select more than one tool.

W3C/WAI does not endorse or promote any single tool or vendor but encourages the development and evolution of Web accessibility assessment tools. An extensive collection of evaluation, repair and transformation tools is maintained by the Evaluation and Repair Tools Working Group.

2. What are Web Accessibility Assessment Tools?

There are several types of tools which can assist in the development of accessible Web sites. These tools can generally provide one or more of the following features:

  1. Evaluation: analysis of Web pages against a set of guidelines such as the Web Content Accessibility Guidelines 1.0.
  2. Repair: automated or semi-automated enhancement of the Web page markup to incorporate accessibility features.
  3. Transformation: modify the presentation of Web pages to assist Web users, but can also be used to identify potential barriers.

Web accessibility assessment tools are usually stand-alone applications but sometimes they can be plug-ins for authoring tools (such as editors, content management systems, or word processors), or Web browsers. A few assessment tools can also be configured to run on an ongoing basis to monitor the status of Web sites.

3. What is the Intended Usages for Web Accessibility Assessment Tools?

Typically, Web sites go through different development stages such as design, implementation, and operation. For each of these stages, different roles of developers may be more significantly involved. The roles involved in the development and maintenance of Web sites can be roughly categorized into the following:

Each of the groups listed above have different requirements to effectively carry out their tasks. For example, while user interface designers may be more interested in assessing and incorporating accessibility concepts in the overall visual design of the Web pages, application developers may be more interested in assessing and incorporating accessible code in the markup of the Web pages.

In order to determine suitable Web accessibility assessment tools for your specific organization, a carefull analysis of the internal development processes needs to be made. In some cases, one or more roles may prove to be more important than others. For example, a Web development agency may not have a need to focus on content development issues such as appropriate language usage. This may however be the main concern of a content provider. It is also common that developers have more than one role within an organization, or that some roles are not present at all. For example, small Web sites may not involve application developers or differentiate between them and content authors.

By analyzing the target audience for Web accessibility assessment tools, specific requirements can be identified. In some occassions, a single tool may be able to address these requirements; for example by being configureable. Sometimes, it may be necessary to utilize more than one tool to satisfy different requirements. For example, while evaluation tools may better assist application developers and content authors by providing them with detailed reports; transformation tools may better assist user interface designers in learning accessible design concepts.

4. What are the Characteristics of Web Accessibility Assessment Tools?

Apart from the overall evaluation, repair, or transformation functionalities, Web accessibility assessment tools can have important characteristics which need to be considered during the selection process. Depending on the type of Web site and organization, some of these characteristics may be more or less relevant. Involving the affected stakeholders in analyzing the importance of each of the following characteristic is necessary in order to select suitable assessment tools.

User Interface

There are several types of user interface paradigms which are employed by Web accessibility assessment tools. Some tools generate comprehensive reports which can sometimes be customized. This may be requested by more experienced users or technical developers who want to quickly look for errors and fix any broken markup. Other tools provide wizard dialogs or display (potential) errors within the Web page to hide as much of the technical details as possible. This may be more suitable for less advanced or non-technical users. It is very important to select tools which employ suitable user interfaces to effectively assists the users in performing their tasks.


Only a few Web accessibility assessment tools are available as plug-ins for authoring tools such as content management systems, editors, or word processors. For some users, such tools might increase their productivity by integrating the assessment features into their development tools. For example, a visual designer may prefer to have an integrated color contrast assessment tool within their graphics tool rather than exporting the images in order to be able to analyze them. Content authors may prefer to have an evaluation tool which is integrated into the content management system rather than having to publish the information in order to assess its accessibility in an additional step.


Users want to rely on tools to assist them in making correct decisions. It is important to realize that evaluation tools may provide false results, repair tools may repair markup only inadequately, and transformation tools may convey wrong understanding for accessibility requirements. The selection of suitable Web accessibility assessment tools should involve the analysis of the tools with regard to their precision. Also technical factors of the Web site such as its size and complexity may affect the precision, especially of evaluation tools.


Tools can sometimes also adapt to the specific requirements of an organization or user. For example, evaluation reports can sometimes be customized to a high degree making them suitable for several types of users. Also repair tools can sometimes be customized in order to increase its effectiveness. Especially larger organizations or specialized Web sites may want to investigate the configureability of the tools during the selection phase in greater detail.

5. How do User Roles Map to Requirements for Web Accessibility Assessment Tools?

As discussed in the previous section, the roles of the users involved in the development stages of a Web site determine the main intended usages of the Web accessibility assessment tools. This section will highlight some of these roles in more detail as well as describe the requirements which these user groups tend to have.

User Interface Designers

User interface designers are responsible for developing the overall design and navigation of a Web site. Visual and structural layout of the Web site has a significant impact on the overall accessibility which the designers may not be aware of. Web accessibility evaluation tools may sometimes be able to assess conceptual barriers only to a limited extend. For example, it is very difficult for an automated tool to adequately assess the accessibility of a site-wide navigational bar. Even though transformation tools may not always be capable of identifying divergence from Web accessibility guidelines, they can be very useful in educating user interface designers in how to incorporate accessibility concepts on a Web site.

Application Developers

Application developers are responsible for the functionality of a Web site. Coding server-side or client-side scripts, and template markup may be their main areas of concern. Application developers need to develop robust functionality which can render on the widest range of browsers such as some types of assistive technology for example. Depending on their capability and precision, many accessibility barriers within Web applications can be addressed by evaluation or repair tools. Sometimes evaluation tools may not be able to automatically determine specific accessibility barriers but are often capable of determining if potential barriers are applicable or not across a whole Web site. This feature may be especially effective for large Web sites.

Content Authors

Web content authors are usually non-technical users who publish information with the help of authoring tools such as content management systems, editors, or word processors. Web accessibility evaluation and repair tools can often address many of the accessibility barriers within the markup of the generated content. Often Web content authors may be more interested in evaluation and repair tools which can provide feedback in a simple format that is easy to understand. For example, some evaluation and repair tools provide extensive educational resources or employ wizard dialogs to carry the users through each step of the process rather than generating comprehensive reports with line numbers and error messages.

Project Managers

Web project managers are usually more interested in a higher level view on the status and progress of the Web site. Some Web accessibility evaluation tools can provide statistical summaries and overview reports intended for project managers. Sometimes evaluation reports can be customized to a sufficient extend or the tools can output the reports in machine readable formats such as XML or EARL. These reports can then be processed and analyzed by other specialized analysis tools.

Last modified: $Date: 2005/01/27 12:51:20 $ by $Author: shadi $

Note: This draft WAI Resource developed by W3C/WAI's Education and Outreach Working Group (EOWG). We invite review and discussion. Please address your feedback to, a mailing list with a public archive. Change log available.

Last updated 14 December 2004 by Shadi Abou-Zahra. Editors: Shadi Abou-Zahra and Judy Brewer, with assistance from participants of the EOWG.

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