Fangs: The Firefox Screen Reader Emulator Extension

Last week I started development of a Mozilla Firefox extension to emulate screen reader output. It is by no means ready yet, but I am releasing version 0.51 in the hope of receiving some friendly feedback and suggestions. I have decided to call it Fangs. The code is released under the GPL license and all source is included in the XPI file. The project is registered at SourceForge where bugs and feature requests can be submitted. Right now, I have only tried it in Firefox version 1.0 on Windows XP. News from other platforms are greatly appreciated (see below for contact details). Update: The OS X bug where a user could not close the window has hopefully been fixed. Update: Version 0.52 adds text selection. Update: For future information about Fangs see the new Fangs information page.

What does it do?

Fangs creates a textual representation of a web page similar to how the page would be read by one of the modern body-part named screen readers. Right-clicking a page and selecting Fangs from the Firefox context menu will open a popup window with the text representation of the page. The output looks like this.

If you install the extension you will find many things that remain to be done as well as some known bugs. However, if you have read my previous post on accessible title tag separators you may be interested in taking a look at your own website title.

How do I get it?

Before you download the extension please note that I accept no responsibility for the effects of this code. It may make your computer burst into flames for all I know.

The Firefox XPI file can be downloaded from here. Installation instructions:

  1. Make sure you have Firefox version 1.0 or later (not the preview release).
  2. Save the Fangs.XPI file to your hard drive.
  3. Open the Fangs.XPI file from Firefox (File menu – Open).
  4. Restart Firefox.
  5. Done. Go to a web page, right-click and select Fangs from the context menu.

How can I help out?

Please report bugs and feature requests at the SourceForge project page. If you are too lazy to do that, drop me an e-mail at

For news about updates please subscribe to the fangs-release mailing list.

Please note that:

  1. Using Fangs does not replace testing your pages with the real thing. If you haven’t bought a decent screen reader already you should do so immediately. It belongs to tools of the trade just like any other application you are using.
  2. I have not set up the SourceForge CVS repository yet so I kindly ask you not to link directly to the XPI file here. In the future, new versions will likely be available from the SourceForge project page.


  1. dusoft says at 2004-11-23 23:11:

    Very nice and keep up good work! Also, write about these interesting topics. We can’t get enough Accessibility ;-)

  2. hemebond says at 2004-11-24 07:11:

    Um. It’s stopped working. It shows “dash Mozilla”, and that’s it. Also the homepage specified “” returns a forbidden error.

  3. Pete says at 2004-11-24 08:11:

    Hemebond: Hey, it is version 0.5. I would be very grateful if you could report the bug at the SourceForge bug page. I will be releasing a new version tonight (Sweden timezone)

  4. Joshua Kaufman says at 2004-11-24 11:11:

    Great idea! But I have a few reservations. Is the Fangs engine in any way related to JAWs? If not, how can I trust the accuracy of Fangs’ output? I would love to see more advancements on this! How can I stay abreast of updates to Fangs?

  5. Pete says at 2004-11-24 11:11:

    Joshua, I have not yet found out if it is ok to claim that Fangs is a JAWS emulation. Obviously I would like to be able to say that. For now you will have to look at the Fangs output and decide for yourself which screen reader it is most similar to…

  6. Tim says at 2004-11-24 12:11:


    Have you considered making the text selectable so that OS X’s “Services > Speech > Start Speaking” facility is available?

  7. Pete says at 2004-11-24 13:11:

    Tim, that is bug #1071542. Stay tuned for more updates.

  8. Tim says at 2004-11-24 13:11:


    Thanks – I’ll take a look.

  9. encyclo says at 2004-11-24 14:11:

    A very nice bit of work: congratulations!

    I can confirm that it works just fine in Firefox 1.0 running on Linux too (an ancient copy of Mandrake 9.1 to be precise).

  10. robert says at 2004-11-24 15:11:

    Nice work i’m running Fedora Core 3 with Firefox 1.0 and it works fine!

  11. Aries says at 2004-11-24 15:11:

    Thank you!

    – Aries

  12. Claus Thøgersen says at 2004-11-24 21:11:


    There is a project working it seems on a plugin with more or less the same capabities, but the the plugin here is supposed to feed text into JAWS. Anyway maybe there could be some joined development.

    Here is their description: 7. Usage instructions:

    This is a proof of concept release. Our scripts support the native Firefox navigational hotkeys as well as some web page reading functionality. Our Firefox extension will reformat a web page so that it can be read back sensibly. If you wish to try this functionality, please install our extension and manually activate the reformatting function before using our JAWS scripts to read back the webpage.

    For a complete list of supported hotkeys, please refer to this page:

    The following web page reading commands are currently supported: Read the current section: Insert + DownArrow Read the next section: Insert + PageDown Read the previous section: Insert + PageUp

    The Firefox page reformatting extension can be accessed by doing the following: Select the “Tools” menu. At the very bottom, the should be a submenu labeled JAWS. Select it. In the submenu, there should be an option labeled “Format Page”. Select it. The page should now be formatted in a way that is readable to JAWS. (Note that the formatting disappears when the page is refreshed.)

    Currently unsupported: Recognizing the number of headings and the number of links on a web page. Automatic reformatting of a webpage before it is read back. Maintaining the normal appearance See more here: of a webpage after reformatting.

  13. Hermann says at 2004-11-25 17:11:

    Hi to all, I think creating a plugin for Firefox instead of adjusting it to many different screen readers is a better idear, because it makes the access of websites screen reader independent. To watch such a fully developped plugin at work, you should download the Webformator – a plugin for MS’ IE – developped by the German company Audiodata. To do this see:

  14. Robin Lionheart says at 2004-11-26 07:11:

    Might be useful in conjunction with the FoxyVoice extension. ( Maybe you should be working together.

  15. Anonymous says at 2004-11-29 19:11:

    I downloaded and visited Google. First thing I notice is how tables obscure content.

    Good bye.

  16. Manoloweb says at 2004-11-30 23:11:

    Comment #15 just took the words out of my mouth. This could be a free replacement for those expensive screen readers. another project suitable for partnership (or work-together) is

    Great job!

  17. EvilDentist says at 2004-12-04 10:12:

    awesome project! :D keep up the good work!

  18. solo says at 2004-12-17 10:12:

    Thank u very much for this plugins. It really useful for thoses who are interested in acessibility of websites :D

  19. Shanni says at 2005-01-31 07:01:

    Hey, anyone else tried this new Fire Vox thing?

    Still early in development, but it looks promising – this guy is putting all the features of a screen reader right into Firefox via a talking extension!

  20. Pete says at 2005-02-03 21:02:

    Shanni, Fire Vox solves a different problem than Fangs. Fire Vox is a tool for vision impaired users that need to access a web site. It will not help you test how a web site would look for a typical screen reader user.

    I find it difficult to understand how Fire Vox can help vision impaired users. Screen readers need to be on the operating system level. If the tool is only available in the browser, how do you get into the browser after starting your computer?

  21. steve says at 2005-10-12 05:10:

    Someone blacklist John (#21-26).

    A great little tool. Well done!

  22. John says at 2005-12-05 15:12:

    Any timeline for FF 1.5 support?

  23. baldo says at 2006-01-12 12:01:

    1.5 firefox support!!!!!!

  24. Piloue says at 2006-02-21 11:02:

    Damed, it does not work with FF 1.5 :(

  25. Peter Krantz says at 2006-02-22 13:02:

    Please check version 0.9.9 for initial FF 1.5 support. There may be some bugs, but it will hopefully work.


Peter Krantz, (remove giraffe).