Acc - an Accessibility Evaluator

Acc - an Accessibility Evaluator is a developing Firefox Extension, which is capable of evaluating and reporting some accessibility criteria. This proof-of-concept demonstration reveals vast possibilities of web browser -based website accessibility evaluation.


Acc - an Accessibility Evaluator prototype version 1.0.2:

Further development

Extension development is continued by Foxability-project. Foxability is going to be modular and extensible accessibility analyzing extension.


Open the file with Firefox and give priviledges to install the extension. Restart Firefox and you should see Evaluate Accessibility option in Tools menu.


Acc - an Accessibility Evaluator tries to do what other evaluators can't do. It includes basic explicit test for HTML, but also includes features like

Known Problems

If you have a slow processor like Pentium III at 1GHz, layout extraction process on large web site may take more than five seconds which is default maximum time for script runtime. Solution: point your browser to about:config, search for property dom.max_script_run_time, double-click it and set maximum running time to 20 secs or more.


Source Code

The source code is inside xpi-package. UnZip the acc.xpi. UnZip acc.jar in chrome directory. .js and .xul files in content directory are probably what you are looking for.


Acc - an Accessibility Evaluator is licensed under GPL.

For other licensing purposes, please contact author (

Master Thesis

The extension development work is part of my Master Thesis (in Finnish):

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© Antti Ekonoja ( <>
Tommi Lahtonen ( <>
Jukka Mäntylä ( <>
2011-03-01 11:48:29
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