Works perfectly for my use case: needing a few of my pinned tabs to be more recognizable.

Note that the logo needs to stay square in shape, otherwise it will be stretched.

Very useful. I have just tried it and it changes any website favicon beside the tab title like a charm. But it don't change the favicon in the bookmarks, only the websites without favicon is changed in the bookmarks but the rest which have an icon already don't change. Thanks anyway for the addon.

I have been looking for something like this for YEARS!!! THANK YOU!!!

The only thing I would change or request so far is the ability to use wildcards in the URL - so I could have one entry for an application that takes care of each of my three environments (instead of having to have 3 entries for the same image). Alternatively, the ability to assign multiple URLs to the same image would work as well.

This is exactly what I needed! I like to keep my bookmark toolbar as clean as possible with only icons, but some sites don't have favicons specified and I didn't want them all looking the same, obviously. It could use a bit of documentation on use, as the average user would expect to see some sort of icon to click or something to bring up the options or a new menu option in Page Actions. Otherwise, this is perfect and I hope it stays around!

It doesn't work with my 60.9.0 ESR release. Any way to get it fixed??

- update (03/12) -

Now it works!! Thank you. :-)

But it doesn't support .ico icons. The .ico files have to be converted to .png format.

There is a concern when adding a new favicon to the system when there are others implemented. The Custom favicon function for the implemented favicons shows "No file selected" even though there is an icon shown to the right of the Name entry field.

Works well on last Firefox and do the job great! Will be good to allow remote images as source of favicons, instead of local files upload.

Works perfectly for me! Was able to completely customise the favicons of various websites in the browser window as well when saved as a bookmark in the toolbar.

# Do note that once you customise a website's bookmark favicon, you'll have to delete all occurances of that website from your browser history in order for you to update the website's favicon with a new one (new ones wouldn't show up for me otherwise).

Worked great, just leave the string box empty.

You do need to close and reopen the tab after restarting FF though.

Love it, exactly what I needed.
Accepts any sort of picture I tried, not just .ico
Would be great to have some built in icon replacement options.

Great experiment! Do not stop!
An incredibly useful tool for optimizing workspace, completely solves the problem with chaos in the tabs, when they do NOT have their own favicon.

Great add-on. Just go into addons and then preferences to configure

Great add-on, works just as shown, including in the new WebExtensions versions of Firefox. Thanks!!!

Quantumになって、ファビコンカスタマイズのアドオンが見つからず、残念に思っていましたが、
このアドオンでカスタマイズがまた可能になりました。使い勝手も良いと思います。

1）ファビコンをカスタマイズしたいブックマークのURLをコピー
2）アドオンの詳細画面でURLの欄にCtrl+Vでペースト
3）png形式の画像をcustom faviconの欄に選択した後
4）ファイアフォックスを再起動
5）ファビコンを変更したブックマークを選択してホームページを表示することで
新しいファビコンイメージが表示されます。