Firefox : addons, configuration and some tips


Categories: logiciel Tags: firefox web


Mozilla Firefox is a web browser developed by the Mozilla Foundation. It uses the Gecko rendering engine, the only serious competitor to the Google Chrome engine which powers most web browsers (including Google Chrome, Opera, Vivaldi, Brave Browser or the latest Microsoft Edge).

Unfortunately Firefox has been constantly losing marketshare to other browsers. According to, Firefox would only accounts for 6.40% of the total market share.

Yet Firefox has many strengths for those who want a modern, ethical and privacy-friendly browser.

In this post I present the essential addons I use, two very practical yet not widely used Firefox features as well as some configuration options I apply.


Privacy / Security



Interface customization

One of the truly unique features of Firefox is the ability to deeply modify its interface. This feature is available in the Customize… menu available in the Firefox settings menu or by right-clicking on the URL bar or bookmarks bar.

Among the bars that make up the Firefox interface, all but the menu bar can be edited. It is possible to display or not the menu bar and the personal bar, the other two can’t be hidden.

Available interface elements can come from Firefox or installed extensions. Thus Firefox icons such as Settings, Home, Downloads or the icons of the extensions can be placed anywhere on the above mentioned bars. Some items such as tabs, the URL bar or navigation buttons cannot be removed but can be moved.

The Flexible Space element is the only element that serves only an aesthetic function: it is used to fill an empty space (by the way, the default Firefox layout uses this element on each side of the URL bar).

At the bottom left are options to add toolbars (menu bar, personal bar), change the theme (default, light, dark or afterglow) or change the density of the interface (from the smallest to the largest, compact, normal, touch).

Default configuration

4 possible themes

3 levels of density

My configuration

The configuration I use is made with the following options:

The elements of the personal bar (containing the bookmarks) are placed at the URL bar level, and the elements of the extensions are moved to the tab bar (when installing an extension they are automatically placed at the right of the URL bar).

A tip to have only the favicon of the bookmarks is to remove the title. Don’t forget that in order for the bookmarks to be in the personal bar items, you will have to select the personal bar folder when saving.

It is possible to go even further in customizing the Firefox interface by modifying the userChrome.css file (here the term Chrome is a reference to the shiny metal and not to the competitor browser, which, by the way, doesn’t allow such extensive modification of its interface). It is possible to see some examples of advanced configuration on the FirefoxCSS subreddit.

Keyword search engine

Another less known feature is the possibility to add search engines and add a keyword to them.

The easiest way to add a search engine to Firefox is to right click in any search field and select the option Add a keyword for this search.

You will then be asked to choose a keyword for this search, for example wiki. Once the engine is added, a search for wiki linux will automatically redirect to the search for the word “linux “ on this search engine.

This feature is equivalent to the bangs from DuckDuckGo or qwicks from Qwant (you need to prefix the search engine keyword with ! for ddg, and ! or & for qwant). The disadvantage of Firefox’s functionality compared to that built into DuckDuckGo or Qwant is the need to manually add each search engine. On the other hand, the search will be faster because the URLs will be resolved locally instead of being sent to a remote server, and you will have the choice of the keyword used for the search.

Internally, these search engines are just bookmarks, with slightly different attributes:

It is even possible to go further by using this feature as a URL builder. Let’s take the example of Lastfm, a website allowing to record its listening history and offering statistics and associated recommendations.

A search for the Radiohead group on Lastfm is done via the URL In this case, the search is unambiguous and the searched group is in first position in the list of results. Since we already know the name of the group, it would be faster to go directly to the artist page without going through the search page using the URL

In the same way as before it is therefore possible to use shortcuts to directly reconstruct the artist’s URL. I personally use the keywords lfm and lfmd (d for direct) to respectively use the Lastfm search or to directly access an artist page.


Here are the main settings I apply to in the Firefox options (page about:preferences). I use the Firefox Sync function to save and synchronize these settings.


I enable this option because I prefer to systematically choose the location where I save the files I download rather than having everything saved in the Downloads folder.

Allows you to use the wheel click to scroll through a page.

By default, this setting is enabled, which makes the scrolling of pages “smooth”. This is useful if you are using a touchpad but makes navigation quite unpleasant when scrolling with the mouse wheel.

Privacy and security

Firefox warns that some sites might not work well, but I personally have never had a problem.

Systematically sends a signal DNT (Do Not Track) to websites. Paradoxically, this feature can help to track websites since relatively few users use this option. I activate it on principle.

Used to disable the password manager built into Firefox.

user.js file

In addition to the options available in the Firefox settings, there are others that can only be accessed through the Firefox about:config page (more precisely, all Firefox settings are present on about:config even those presented above, but only some of them can be modified from about:preferences).

Although it is possible to change the options manually via this page, it is also possible to create a user.js file containing these parameters with the syntax user_pref(“key”, value). This file must be placed in the folder of the active firefox profile. Under Linux this folder should be in a location similar to ~/.mozilla/firefox/1234.default-release/. Once the file has been placed in the correct location, a restart of the browser will suffice to apply the new settings.

In the examples below, I have selected only the options that I thought were most important. You can find the complete my user.js file on github.

Tab behavior


Privacy / Security

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