Validators & Simulators

The tools listed here can help web developers make websites accessible. There is no tool that can evaluate web content for all types of accessibility errors. A human check is always necessary.

Web Developer Toolbar
This extension to the Firefox or Chrome browser adds a menu and a toolbar to the browser with various web developer tools. Tools include links to validators, outlining of images with missing alt text, hiding images, disabling styles and javascript - plus many more. This tool is a must-have for web developers.
Illinois Firefox Accessibility Extension
This Accessibility Extension makes it easier for people with disabilities to view and navigate web content. Developers can use the extension to check their use of structural and styling markup that support functional web accessibility.
Accessible Information Solution Toolbar for Internet Explorer
The Web Accessibility Toolbar has been developed to aid manual examination of web pages for a variety of aspects of accessibility. Good for users who have only have Internet Explorer on Windows.'s Colour Contrast Check
The Colour Contrast Check Tool allows to specify a foreground and a background color and determine if they provide enough of a contrast "when viewed by someone having color deficits or when viewed on a black and white screen"[W3C]. This web-based tool will indicate that the colors pass the test if both the color difference and the brightness difference exceed their threshold.
Juicy Studio's Colour Contrast Analyser Firefox Extension
This Firefox extension reveals the color contrast of all elements in the DOM (Document Object Model). If you evaluate websites for color contrast, this extension will be useful for saving you time, and also take out the guesswork required to determine which colors to test. This will not test color contrast in images.
Pacello Group's Contrast Analyser
Primarily a tool for checking foreground & background color combinations to determine if they provide good color visibility. It also contains functionality to create simulations of certain visual conditions such as color blindness. Download available for both Mac and Windows.
Jaws - Screen Reading Software Demo Version
The most popular full-screen text reader, Jaws®, is available in a demo version that runs for 40 minutes at a time before requiring the computer to be re-booted. Jaws is not required to evaluate all web content, but is good when verifying Flash and other rich media content, or when you're not sure how specific content might be read or accessed.
Web Accessibility Toolbar For Internet Explorer
This Internet Explorer extenstion aids manual examination of web pages for a variety of aspects of accessibility. Similar to the Firefox Web Devoloper Toolbar.
W3C HTML Validator
The first step in creating accessible pages is to write valid code. Make sure your HTML validates. The Firefox Web Developer Toolbar includes a referring link to the W3C Validator. Validating HTML is a required step in the CSU Manual Evaluation Method.
W3C CSS Validator
Validating your CSS is an important step in accessible design. Using standardized CSS code will ensure the broadest possible support among different browsers, platforms, mobile devices and assistive technology. This is also a required step in the CSU Manual Evaluation Method.
HiSoftware AccMonitor and AccVerify
AccMonitor is a server-based monitoring application. It can crawl websites, check for accessibility problems, and produce reports for campus web developers. AccVerify is a desktop application campus web developers can use to repair accessibility problems in web pages, and document accessibility compliance. AccVerify is only available on Windows. Like all automated tools, these cannot detect all accessibility problems, so manula evaluation is still necessary. However, AccMonitor and AccVerify are good for monitoring sites and can alert you when certain problems sneak in. These also include site quality reports such as Link Error, Repetitive Link Phrase, Title Element Error, and others. Contact Barbara Moore, Director of Web Services, for further details and to set up periodic reports for your site, or see this sample AccMonitor report.
Cynthia Says Web Content Accessibility Report
The HiSoftware Cynthia Says Portal can check a web page to see if the content meets Section 508 Accessibility Standards. The report generated gives valuable advise on what's wrong and how to fix it. Cynthia Says can not check for all aspects of accessibility or 508 compliance (human checks are still needed), but it's a good first pass that will indicate where a page may have problems.
This web-based tool provided by WebAIM helps developers find accessibility errors and possible errors in web pages. See the Using WAVE overview for information about how it works.
Formerly a free service, but now owned by commerical corporation Watchfire, Bobby can help web page authors identify accessibility problems. There is a limit to the number of URLs you can check in a given time period, so Bobby may not be the most effective tool for accessibility-checking.
Check images and image-based web designs with Vischeck to simulate what users with color-blindness will see.
Perform color correction to make images accessible to color-blind users.