AChecker is an open source Web accessibility evaluation tool. It can be used to review the accessibility of Web pages based on a variety international accessibility guidelines. Use the Public AChecker to evaluate the accessibility of a Web site you know. Download AChecker to setup your own version.

Accessibility Guidelines Supported:

  • WCAG 1.0 (International)
  • WCAG 2.0 (International)
  • BITV 1.0 (Germany)
  • Section 508 (U.S.)
  • Stanca Act (Italy)

Why is AChecker Different than Other Accessibility Tools?

Automated accessibility checkers can only identify a limited number of barriers in Web content with certainty. A human must interact with an accessibility review to make decisions on potential problems automated tools can not identify. For example, any check that requires the evaluation of meaning, such as whether link text accurately describes the purpose of a link, or whether Alt text sufficiently describes the meaning contained in an image, a human must make a decision. If an accessibility checker is not asking the evaluator to make manual checks, it is not doing a thorough job.

Evaluating accessibility with AChecker is an interactive ongoing process. AChecker knows when it is unable to identify a potential problem and will ask the evaluator to manually check for the problem. Because Web content often changes, AChecker can be used to monitor the accessibility of Web content as it evolves. Linking the AChecker conformance seal from a completed evaluation into a Web page, indicates the site is serious about accessibility. Clicking on a seal retrieves the original evaluation from AChecker, or it runs the evaluation again if the content of the page has changed.

AChecker also allows users to create accessibility guidelines, if for instance they are working in an enclosed environment that requires a specific level of accessibility. It also allows users to create new checks for the system as technology develops and makes it possible to check issue that may not have previously been possible. It is also an open system, so those who want to develop expertise in accessibility evaluation have full access to all the inner workings of the system, all the accessibility checks and the solutions for fixing problems found by the system, and a full range of test files that verify exactly what each accessibility check is checking.

How to Use AChecker

  1. Enter a URL to a Web page, upload an HTML file, or paste HTML from the clipboard.
  2. Review Known Problems and make the suggested corrections to the Web page, then run AChecker again. Known Problems are those that AChecker knows with certainty are accessibility barriers.
  3. Review Likely Problems. Likely Problems are those that AChecker has identified as probably barriers, but can not be sure. They require a human to make a decision. Login, then answer the questions to confirm if likely problems are actual problems, and make corrections to the Web Page where likely problems are confirmed. Save your decisions after all Likely Problems are resolved.
  4. Review all Potential Problems. Potential Problems are those that AChecker can not identify, that require a human to make a decision. Answer the questions to confirm if potential problems are actual problems, and make corrections to the Web page where potential problems are confirmed. Save your decisions after all Potential problems are resolved. When all Known, Likely, and Potential problems have been resolved, a Conformance Seal is issued.
  5. Paste Conformance Seal into Reviewed Web Page. Copy the HTML generated after completing an accessibility review into the HTML of the reviewed page. Run AChecker again on the Web page, which will recognize the addition of the seal as a change, and resolve the new Likely and Potential problems. You may copy the conformance seal to a local folder, and adjust the path to the image in the copied HTML.

AChecker Features

Regular Users

  • Accessibility Checking: Set the standard against which to evaluate your Web page, then generate a report of Known, Likely, and Potential accessibility problems.
  • Markup Validation: Turn on Markup Validation, to validate your HTML while reviewing accessibility.
  • Stylesheet Validation: Turn on CSS Validation, to validate your stylesheets and inline styles while reviewing accessibility.
  • Display Source Code: Turn on source code for quick review of the HTML surrounding places where accessibility problems are identified.
  • Generate Downloadable Reports: Export accessibility reports in PDF, CSV, HTML, or EARL files.
  • AChecker Handbook: Throughout AChecker, open the handbook for a description of how things work.

Registered Users

  • Save Reviews: After resolving all issues, and answering all questions for likely and potential problems, save your results to generate an AChecker seal that can be added to your Web site and linked directly to the saved review.
  • Customize Standards: If you need an accessibility standard other than those included with the system, design your own by selecting a subset of all the accessibility checks available in the system.


  • Manage Users: Manage users on the system, and assign them to various user groups with various permissions to perform AChecker related tasks.
  • Manage Groups: Create groups and assign permission to groups to: use AChecker, manage users and groups, manage guidelines, create and edit accessibility checks, add and remove languages, and permission to translate AChecker.
  • Guideline Management: Manage the existing guidelines, add new guidelines, and approve guidelines developed by other users.
  • Check Management: Manage all aspects of the accessibility checks in AChecker. Modify text, adjust check functionality, or create new accessibility checks.
  • Language Management: Import language packs to make AChecker available in different languages. Translate AChecker if the language you need is not yet available.
  • Profile: Manage your personal information stored in AChecker.


  • Web Services API: Developers can query AChecker from within their Web applications using the REST protocol, and have accessibility reporting as an integrated feature of their applications.
  • Public Source Code Repository: All AChecker source code is available for public Checkout from our Subversion version control system.