Understanding Axe and Attest Extension compatibility with Firefox

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If you're currently using our aXe Firefox extension, WorldSpace Attest extension for Firefox or FireEyes II, this message is for you. To ensure full functionality of these tools, this post intends to help you understand which extensions work best on specific versions of Firefox.

To start, this shortcut guide maps the product version you might be using, with the compatible version of Firefox recommended for use.

Product nameCompatible Firefox Version Relevant links
aXe extension 3.2.1 (uses aXe-core rules 2.4)Firefox 54+Latest aXe extension
aXe extension 2.0.5 (uses aXe-core rules 2.4)Firefox 53x & belowDownload legacy aXe addon
WorldSpace Attest extension 1.3 (uses aXe-core rules 2.5)Firefox 54+
FireEyes II (uses aXe-core rules 2.4)Firefox 54 & below

Using the aXe Firefox Extension

If you're using aXe extension version 3.2.1, please use Firefox 54+. Unfortunately, the store and extension will not prevent you from installing the latest extension on a previous version of Firefox.

How will you know if you have the wrong versions installed?

You can certainly use the versioning table above to make sure the version of your extension and browser are compatible. A good warning sign that will indicate your versions are not compatible is if you're able to launch dev tools but the extension does not appear in tools, even if it's installed. If you're using any version of Firefox prior to 53x please use the aXe extension version 2.0.5 and the legacy aXe addon link provided in the table above.

Attest Extension and FireEyes II

Attest Extension version 1.3 which is due for release December 1st is compatible with Firefox 57+.

FireEyes II is compatible with Firefox versions 54 & below.

Licensed customers can contact helpdesk@deque.com for the extension needed to match your browser type.

Screen Reader Users

Users that utilize screen readers are reporting several issues when attempting to use the latest release of Firefox. The National Federation of the Blind recommends that screen reader users use the latest ESR Release which at the time of this publication is 52.5.0esr. You can download the latest ERS release here.



For over fifteen years, Deque has been helping major corporations, government agencies, and other organizations ensure that their websites and mobile apps are accessible to everyone. We have more than fifteen years of history of serving the federal government, including undertaking the biggest accessibility program that’s occurred in the United States government or anywhere. Deque also works with .edu’s and mission-focused nonprofits to ensure that their materials and systems are usable and barrier free for users with disabilities. The company invented the first accessibility plug-in software, the first web-based testing platform, and the first server-based accessibility solution. All of these have been created in the service of helping our customers become accessible, advance the goals of their organization, and remove barriers for all users on the web.

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