Sehr gut für mehr Privatsphäre!
Hier wird alles hervorragend und leicht verständlich erklärt: https://www.kuketz-blog.de/firefox-smart-referer-firefox-kompendium-teil6/
Dort steht als Fazit geschrieben: Über welchen Suchbegriff ein Besucher auf eine Webseite gelangt ist oder welche Webseite sich jemand gerade anschaut, mag für einige Protagonisten eine wertvolle Information darstellen. Aus Nutzersicht kann die Sammlung und Auswertung der HTTP-Referer-Informationen allerdings einen Eingriff in die Privatsphäre darstellen, den niemand einfach tolerieren muss. Mittels Smart Referer wird der ursprüngliche HTTP-Referer so umgeschrieben, dass der jeweilige Empfänger daraus keine verwertbaren Informationen extrahieren kann.

Far from smart... Requires a lot of work to un-break all the internet it breaks. (As there is no easy way to add exceptions - and you will need a lot of exceptions.)
Having a UI for that like adblockers do would help. Something that does not require copying URLs into preference-section of the extension.

Great

It used to work fine for me... until the last update. One should never activate "automatic updates"!.
I use Firefox-ESR under Debian Linux 8. After the update, SmartReferer just doesn't send the Referrer to xyz.eu, though i have defined an exception * xyz.eu. I didn't change a thing, a few days ago, it still worked all right. Is there a way to install the old version?

It breaks video playing in facebook. --- 'fbcdn.net/*.mp4' files are blocked by CORS security.

I had a look at the exceptions rules and it already has '*.facebook.com > *.fbcdn.net'. The exception rules are not working anymore? Have to disable to be able to watch videos.

Only way to find out this was the cause of the error was to enable/disable obvious culprits like ublock, decentral eyes, etc.. one by one, and this addon was not at the top of the list.

Does exactly what it says.

There's no telling if this add-on works or not. It doesn't offer any notification of any kind.
I give 2nd star in a good faith that at least it does what it says.

A nice way to keep your navigation private. Thanks for this!

The developer's description of this Fx extension is woefully inadequate.
It fails to explain what the extension does, why and how it does what it does, and (most importantly) what particular issue(s) the extension is designed to address. I ask the developer to please rewrite the description so that it is meaningful to every casual reader (and even to an Fx longtooth [v1.2] and privacy freak who, from the description, has no clue about what this extension is "for").

It's not 100% perfect, e.g. no Chrome version, a few bugs here and there, but all in all this seems fantastic. Nothing else seems to encapsulate this functionality (except Tor Browser), which is really a shame. The referer header is a significant source of information leakage which has been around since the web was invented. I'm surprised that this extension is perhaps the only way to defend against such leakage with ease. It certainly brings a greater peace of mind with respect to people being able to track your movements.

ขอบคุณ

fine :)
smart :)
simple :)

Also for Chrome, Opera? :)

When i have enable the addon, i can't watch videos on Facebook...by disabling the addon everything is ok. The problem is only on FB...please fix that issue.
Windows 7 64bit Firefox 61.0 beta 13

Good