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Prevents Firefox from storing entity tags by removing ETag response headers unconditionally and without exceptions. Minimalism at its fullest.

WARNING: ETags for resources that were cached prior to installing this will remain intact. You will have to manually clear the cache once to remove existing ETags after installing this extension.

I was using a more general-purpose extension for editing headers, but most of the rules I made were only experimental. The only constant across all my profiles was a rule to remove ETag headers. I decided that I didn't need the extra bells and whistles, and so this diminutive extension was born.

This site has a functional proof of concept that you can use to confirm the extension is working as intended. Note that you may need to whitelist the site in uBlock Origin, because that extension can prevent the HTML document from being cached (depending on your personal settings), and the test relies on that.

Keep in mind that ETags are only *one* of the known tracking/de-anonimizing vectors related to the cache. I am aware of at least three other less straightforward methods to exploit the cache for those purposes. If you are absolutely serious about your privacy, do not rely on this extension. Instead, disable the cache and/or use another extension like Temporary Containers in automatic mode.

Might as well recommend you to take a good look at this project if you haven't already. Even if you already use a user.js file to manage your Firefox settings, I recommend you to at least take a good look at the wiki, which is full of valuable up-to-date information for all Firefox users seeking to tighten our security and privacy.