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NVDA has been installed on the Thinkpad departmental laptop. View the NVDA user guide. As it is a Windows application, it works outside browsers. Can be used to test accessibility of documents including PDFs.


Standard caveat for accessibility testing tools - no automated tool can guarantee WCAG compliance of any level as some of the criteria cannot be assessed programmatically. Manual testing will also be required.

Automated tools


 A command line wrapper for HTML Code Sniffer. It also has a display stack which shows the results of tests run on configured sites. Currently, Pa11y only informs of the existence of problems on a given, not the location of those problems. The command line tools are written in javascript and have an api which, with a bit of scripting, would let us run automated checks and (for example) fail them if any Errors are found.

Pa11y v2 is in active development and will remove the dependency on HTML Code Sniffer.


Funnelback tool

Written by Funnelback, this is also a wrapper for HTML Code Sniffer. The processing is thorough, but the output is confusing. Like the Pa11y dashboard, it is far more useful for an overview of our compliance, rather than actually identifying individual problems. There is a cost to this service.

Browser tools

HTML code sniffer

The core of other tools here. Can test against WCAG A, AA, AAA and Section 308. The browser tool is a bookmarklet which identifies and locates the problems, allowing the tester to click through everything located and have it highlighted on screen.

Fangs for Firefox

Screen reader emulation for Firefox (browser-based only). Rather than simply removing stylesheets, this plugin gives a text version of what a user with a screen reader hears. Although different screen readers will behave differently, according to Tim this gives a good representative output. Support for HTML5 is limited.


Screen reader emulation for Chrome (browser-based only).


Screen readers

  • NVDA - free screen reader
  • JAWS - proprietary screen reader, evaluation license available
  • Dragon - proprietary screen reader