NVDA – a free and open source screen reader for Windows

People often ask on the various accessibility related forums and mailing lists, a question like:

If I wanted a Screen reader program which one should I buy?

For many developers is it worth buying a screen reader product like JAWS or Window Eyes? Its usefulness for providing meaningful results, in regards to the accessibility of a web site or web based application to a screen reader user, is limited by the relative inability of the non-disabled user to appreciate and understand the user experience of a person who has to use a screen reader to interact with the web and desktop applications. The only practical way to gain any sense of this is by sitting down with actual users of assistive technology and observing how they interact with the web and desktop. Another barrier for the disabled and non-disabled users alike is the complexity of screen reading applications, try looking through the JAWS keystroke documentation to get an idea; there are 150+ keystroke combinations just for using the web!

Having said this, it is useful and desirable for developers to have some first hand experience with a screen reader or other assistive technology. For example, it can be useful to test the new web standards based AJAX widget you just developed, to find out if the information that is available visually is technically available to the non visual user, though this information is probably better obtained using tools such as aDesigner or Accprobe, which provide a view of the MSAA or IAccessible2 hierarchy of currently running applications or rendered documents. Furthermore, acessibility user testing will always be required to ensure the actual accessibility of your widget for a screen reader user.

If you do want to experiment with a screen reader, rather than paying out large amounts of cash, why not try one of the free screen readers that are available such as NVDA (Non Visual Desktop Access), a free and open source screen reader for Windows.

Like JAWS and Window Eyes, NVDA uses a virtual buffer to provide access to web pages. When used in conjunction with Internet Explorer it exhibits similar problems (as JAWS prior to version 7.1 and all Window Eyes versions in both IE and Firefox) with JavaScript (including AJAX) based content changes. Used with Firefox it updates the virtual buffer in response to content changes (as does JAWS 7.1+ in both IE and Firefox). So it is useful to replicate the sort of content update issues that occur in JAWS and Window Eyes, when browser content is updated without a page reload.

General Features of NVDA:

• Browsing the web (with Internet Explorer or Mozilla Firefox)
• Reading and writing documents with programs such as Wordpad or Microsoft Word
• Sending and receiving email with Outlook Express
• Using command-line programs in Dos windows
• Producing basic spreadsheets in Microsoft Excel
• General computer management through My Computer / Windows Explorer, Control Panel applets, and other generic Windows tasks.

Further Reading:

• NVDA Project
• NVDA Download
• NVDA Documentation