Before the Section 508 refresh, 508 had the following provision:

(m) When a web page requires that an applet, plug-in or other application be present on the client system to interpret page content, the page must provide a link to a plug-in or applet that complies with §1194.21 (a) through (l). - source

I still see statements like this on websites, for example this one from the National Cancer Institute, usually to highlight things like flash, PDF, and Microsoft Office viewers.

  1. Is such a statement about "plugins" still required by Section 508 or recommended by WCAG? (If yes, can you cite a specific section because I couldn't find one). I think this might not map to the updated 508.
  2. Regardless of 508, are statements like these a good idea to have in 2023? After all, PDF viewers are now ubiquitous and available by default in most Windows, OSX, Linux, and Android installs. Several browsers open them out-of-box. I'd also be weary of recommending specific software to users.

1 Answer 1


WCAG does not require such a statement but take a look at the "Conformance" section of WCAG, specifically section 5.2.4. It talks about "accessibility supported" and "Web content technology" which is essentially an applet, plugin, pdf, etc.

It basically defines what external sources might be needed for accessibility but does not require you to put a statement on your website like Section 508 used to require.

You can get a little hint of such a statement in the "4th Note" where it says:

Note: When citing Web content technologies that have multiple versions, the version(s) supported should be specified.

It's not requiring you to cite other technologies, but if you do, and there are multiple versions of that technology, then cite the version that is accessible.

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