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Firefox Configuration Guide for Privacy Freaks and Performance Buffs


UPDATE: I first published this guide in 2015. I wrote it as much for myself to be able to refer to as i did to share it with others.

I never really felt qualified to be writing such a guide, however i failed to locate a truly comprehensive guide anywhere else that covers as wide a gamut including terminology, preferences, the arkenfox project, system add-ons, user add-ons and how to configure them, profiles, web storage, etc..

i'd like to 'pass the torch', as it were, to someone more capable than i, someone who understands the inner workings of Firefox and the threats to privacy better than i do.

If you're interested in picking up where i left off, let's talk. I do have some conditions however which i think should be acceptable and are very much in keeping with a guide of this kind:

  • you must keep the guide up to date, always - a lot of people depend on this
  • i would like to see it remain as comprehensive as it is, covering all aspects of configuration, add-ons, etc. - a one-stop-shop for FF configuration as it were
  • the guide relies heavily on the arkenfox user.js and i think arkenfox is the best of such projects at this time - their user.js is very comprehensive and the project is very active and i'd like to see it remain an integral part of this guide

End update.

See the revision history at the end for a list of changes.

Before embarking on this journey into the bowels of Firefox, you may want to first read, Tor verses a VPN – Which is right for you?. If you choose to use the Tor Browser, you need not digest this guide.


The following video will provide an overview of one aspect of what it is we're up against and why i wrote the Firefox configuration guides. I encourage everyone to view it, especially if you're one of the many people who aren't worried about surveillance because you 'have nothing to hide'.

Video: Prof Shoshana Zuboff on surveillance capitalism

This guide is long, boring, dry, tedious and somewhat technical, so if you don't feel comfortable digesting it give the The Firefox Privacy Guide For Dummies! a shot instead, however be aware that it doesn't offer quite the same degree of protection.

To understand my personal position regarding the ethical nature of the Mozilla Foundation, read The Mozilla Monster.

WARNING: This guide is not for use with the Tor browser. Configuring the Tor browser as outlined in this guide may/will result in serious risks to your privacy and personal security.

Though this guide is centered around the Firefox web browser, users of other browsers, email clients and Mozilla products may find it useful. If you are interested in hardening the Thunderbird email client, see The Thunderbird Privacy Guide for Dummies!.

Many of us are aware of the immense threats to our on-line privacy and security posed by various technology companies, governments and malicious hackers, any of which may go to great lengths to monitor our electronic communications. Governments and their "intelligence" apparatuses not only spy on each other, but on the citizenry as well and they leverage the services of many corporations to do so, including Microsoft, Google, Facebook, Verizon, Comcast, Amdocs and many, many others. While the data these corporations collect may be used for relatively benign purposes such as targeted advertising, the intentions are usually far more sinister. Governments, intelligence organizations and their contractors present a whole new level of threat. Much of what Edward Snowden has brought to light is not new, but it seems Snowden has presented the information in a way that has captured the attention of a broader range of the public, prompting many to seek ways to mitigate such threats.

While the primary goal of this guide is to help the reader thwart some of the more obvious efforts to track and profile us as we surf the web, as well as increase browser security and performance, understand that i am not an expert in computer security or privacy and there are surely many more variables and vectors for attack than i am aware of. For example, even if you are a knowledgeable, technically proficient and privacy conscious individual who uses open hardware devices running secure, open source software on a security enhanced operating system, and even if you connect to the internet only through Tor, you may still be at risk of being tracked because, disregarding everything else, your unique writing style can be used to identify you. It is not this level of sophistication that i will attempt to address here however. My goal is to share what i have learned over the years as a casual web surfer and computer user who has a hobbyist-grade interest in computer security and digital privacy. Having said that, i believe, and please correct me if i'm wrong, that this guide is currently one of the most comprehensive of its kind in that it its scope includes Firefox configuration, extensions and optimizations. If you want to go further than i can carry you, see the resources section at the end which include the fine article, Improve Your Privacy in the Age of Mass Surveillance. I would also highly recommend using a VPN to help prevent spying by your ISP and other bad actors. That One Privacy Site is a good resource for choosing a VPN, as is TorrentFreak which publishes annual reports regarding many of the popular VPN service providers. Their 2018 report is here.

As with any modern and mainstream web browser, Mozilla Firefox is a highly complex beast consisting of millions of lines of code and hundreds of configuration options, many of which are interlinked, hidden, or undocumented. The modern web browser has reached the point where they exceed the complexity and size of entire computer operating systems in some cases and things can go down the toilet quickly if one starts messing around with browser settings willy-nilly. Poorly coded browser extensions are an additional weak point that can compound the problem. Here we will attempt to accomplish our goals in an efficient manner with a minimal number of carefully chosen and necessary browser extensions.

A trade-off must be expected when we tighten security and privacy insomuch as some websites will cease to function as we expect until the settings for those specific sites are adjusted. Anyone who has used a content filter such as uBlock, NoScript or Request Policy will understand that certain resources must be allowed for a given website to function in an acceptable way. Similar to NoScript however, the process of allowing required resources for a particular website usually consists of a few mouse clicks followed by a page refresh. Nevertheless, be prepared to put a little more effort into your web surfing activities initially and expect the occasional hard-case where more fiddling than usual will be required to get a particular site to work. As adjustments are made to your most visited websites your workload will decrease significantly and the pay-off will be a much cleaner, faster web that is less able to track, profile and fingerprint you, as well as a Firefox that is more resistant to attack.

A note regarding user comments

When reading the user comments on this page, keep in mind that this guide has been around since 2015 and, given the dynamic nature of the web and Firefox, some of the information in comments, including information provided by myself, may be obsolete or entirely wrong. Nevertheless i decided to retain all comments because... nostalgia. If you have any questions, ask.


Add-on/extension: I use these terms interchangeably. A web browser add-on or extension is a piece of software, typically developed by a 3rd party individual or company, which extends the capability of the browser. Web extensions, which leverage the WebExtension API (Application Programming Interface), have replaced the older legacy (XUL/XPCOM) extensions beginning with Firefox version 57. The newer API is essentially the same as used by Google Chrome and some other web browsers. The WebExtension API is severely limited compared to the older API and while this is a plus with regard to browser security and stability, it also strictly limits what extensions are able to do.

AMO: Addons.Mozilla.Org - the Mozilla Add-ons website.

Crapware/malware: I consider crapware/malware to be software that contains code which is not relevant to the functionality users expect. As such, the term crapware, or malware, refers largely to adware, tracking code and any other malicious code with regard to web browser extensions. Much of this garbage is delivered by JavaScript (JS). Crapware is often added to browser extensions by a company or solo developer who wishes to monetize their work and often takes the form of profiling users and selling the data collected by the extension to a marketing company, however much worse is possible.

CDN: A Content Delivery Network is a service that hosts often bloated and insecure reusable content for idiot "web developers" that can't write good code themselves. This may include graphics and libraries which developers can leverage to make building crappy web platforms easier. CDN's often present a threat to our privacy by tracking our web activities and browser security by delivering insecure code. CDN's are used by many millions of websites and therefore the damage potential to both privacy and security is formidable. The use of CDN's is so prolific today that many websites will not function without them and so blocking them entirely is hardly an option.

CSS: Cascading Style Sheets are used primarily to apply visual styling to HTML elements, thus making web pages look pretty, however much like HTML and other web technologies, the capability of CSS has been expanded well beyond its original intention to the point where it too can be used for nefarious purposes.

Domain/subdomain/TLD: In the example '', 'example' is the root domain, 'sub' is a subdomain of the root domain and 'com' is the TLD, or Top Level Domain. You can think of root domains and subdomains as sort of different containers which are used to separate content for a single website. For example, let's assume is focused primarily on information about kittens, but they also might have a web store where they sell paper bags. In order to keep the store content separate, they may host the store on the subdomain ''.

Fingerprinting: Web developers can employ a plethora of techniques in an attempt to identify your computer and thus track your on-line activities, though much of this relies on JavaScript being enabled. Your hardware, web browser and other environment variables all contribute to your uniqueness. This data may be gleaned from such things as querying the browsers capabilities, its cache, its viewport dimensions, what add-ons or plugins you have installed, your display resolution, your locale, your operating system, what fonts are installed and how they are rendered, the Canvas API and much more. This information can be obtained using various techniques, including through HTTP header data and JavaScript. For further information, see A Primer on Information Theory and Privacy and Panopticlick. See also the explanation for 'tracking' and 'web storage' below.

HTTP/HTTPS: Hypertext Transfer Protocol and Hypertext Transfer Protocol Secure are communication protocols used by computers to transmit data over the internet. For HTTP an insecure, unencrypted connection is established between your web browser and the website you're visiting. This is dangerous because such a connection is vulnerable to ISP (Internet Service Provider) snooping and man-in-the-middle attacks. An HTTPS connection on the other hand offers a more secure connection because the data you send and receive is encrypted. Some web servers simply do not support HTTPS however and for this reason, as well as others, i would strongly suggest using a VPN.

JavaScript (JS): A powerful programming language used by many websites to run code locally on your computer. Although JavaScript is used by some websites for legitimate reasons, such as to make them interactive, it can, and often is, used maliciously to perform a wide variety of attacks against the browser and your privacy. Many browser fingerprinting and tracking techniques depend on JavaScript however because it is so widespread and used for so many (largely unnecessary) things, it is enabled by default in every mainstream web browser.

Tracking: Once a unique identity for the browser has been established through fingerprinting, it is then possible to track your web browsing activities both within the same domain and across domains. See also the explanation for 'web storage'.

Web fonts/remote fonts: These are font packages typically hosted by a 3rd party (CDN), such as Google, which a web developer may use to specify how text is displayed on a website because they don't give a crap about your choices. Web fonts present a few problems regarding browser tracking and, potentially, security.

Web server: For the purpose of this document, a web server is a computer that is connected to the internet which hosts (serves) one or more websites, such as this one.

Web storage: In addition to HTTP cookies and object caching, most/all mainstream web browsers also allow a web server to store a great deal of data locally using several other storage methods including local and session storage, indexedDB storage, storage, Etag cache storage, Local Shared Objects storage, Service Workers, offline storage, HTTP Strict Transport Security storage and other methods. Stored data for Firefox may consume up to 50% of your free disk space. If you are concerned about protecting your privacy, trust me, you have far more to worry about than the simple text cookies of yesteryear. The web has evolved and not in a good way.


Code editor

You will need a decent code editor with syntax highlighting to edit Firefox's configuration files. Linux users should have something suitable installed by default, however if you're running Windows i might suggest Notepad++ or PSPad, the latter being the simpler of the two.

Unhide file extensions

If Windows is using you, the geniuses at Microsoft have taken it upon themselves to hide file extensions from the user. You will need to address that stupidity.

Getting Firefox

Though i personally recommend using the stable release version of Firefox, there are other versions such as the ESR (Extended Support Release), however it is usually an older version. There is also a Developer Edition which includes the very latest features (and bugs). While there are many 3rd party modifications and forks of Firefox, including Waterfox, Cyberfox, Pale Moon (or Basilisk from the same developer), etc., i do not recommend using any of them. The small development teams for these 3rd party builds often lag behind regarding security patches and they can be buggy and incompatible with the latest add-ons (Pale Moon doesn't support the newer Web Extensions at all apparently). While some forks may be more privacy-centric out of the box, we can accomplish essentially the same degree of privacy, or better, with the official version from Mozilla.

The user.js file

While the prefs.js file is the primary configuration file for Firefox, the user.js or user-overrides.js file (we'll get into that later) is where all your personal preferences are best kept. In our case we will be using a preconfigured user.js template and then supplementing that with a user-overrides.js file which will be appended to our user.js using a script.

The user.js file we will use is a result of a formidable effort by 'pants' and the rest of the 'arkenfox/user.js' crew and contributors. Their work became rather popular when it was published as A comprehensive list of Firefox privacy and security settings by Martin Brinkmann on The project has since changed names and moved GitHub, but don't download anything just yet.

Firefox post install cleanup

If you have been using Firefox, back-up your current profile before making any changes. If you don't know where your Firefox profile is, enter about:profiles in the address bar and click the 'Open Directory' button in the 'Root Directory' row. The easiest way to backup your profile is to select your profile folder under the /firefox directory and press Ctrl+C to copy the folder, then Ctrl+V to paste it in the same place but with a different name. I might suggest keeping the original name and just appending -bak to the copy. From this point on, all changes should be made to your original profile, leaving your backup profile untouched in case something explodes.

Next, delete all content in your original profile keeping only your bookmarks and whatever else you need if you're not starting with a fresh install. See the article Profiles - Where Firefox stores your bookmarks, passwords and other user data if you need help with what data is stored where in your profile folder.

System add-ons

Packaged with Firefox are a bunch of system add-ons which are installed without your consent and they are essentially hidden (they are not listed in about:addons). Some of these add-ons have been and may currently be used for highly controversial purposes such as collecting data without your consent. Typically i remove all of them, however you may want to keep some of them after researching what they do and whether you need them. On a Linux-based OS these add-ons might be found at /usr/lib/firefox/browser/features and for Windows in \Program Files (x86)\Firefox\browser\features or \Program Files\Firefox\browser\features . You can delete them from the terminal in Linux:

cd /usr/lib/firefox/browser/features
sudo rm *.xpi

These system add-ons will be reinstalled each time Firefox is upgraded. On Windows you can apparently use CCleaner to handle them. If you're running Linux with the pacman package manager (Arch, Manjaro, Artix, etc.), you can prevent their re-installation by editing the pacman configuration file, pacman.conf. Note that this will not work if using Pamac, the GUI package manager, until this bug is addressed. In my case i find it preferable to just bookmark the /features folder in my file manager and then run the command above each time i update Firefox.

Search engines

I recommend reading Firefox Search Engine Cautions and Recommendations which offers information about how Mozilla monetizes Firefox with the included search engine plugins and what can be done to opt out of their affiliate scheme should you so choose. While it may seem, and is in fact contradictory for me to recommend Firefox while suggesting to de-monetize Mozilla, i personally feel it is an ethical move given the utterly stupid and unethical things the company has pulled in the past and continues to do.

Required and suggested add-ons and settings

All of the add-ons listed here are of the WebExtension variety, all of which will work with the latest version of Firefox. Download and configure each add-on one by one. Each of these add-ons are important and so it's suggested to not skip any of them unless otherwise noted.

LocalCDN by nobody42

Note: This add-on is optional since the 'arkenfox' user.js negates the privacy aspect of connecting to CDNs, however LocalCDN will speed-up page loading so you may want to use it. Do note that it can break websites on rare occasions in which case the solution may be to enable the HTML filter option for that particular website, or LocalCDN can be disabled altogether for the site.

Description: Helps to prevent tracking and speeds-up page loading by using local copies of common JavaScript libraries rather than fetching them from a CDN.

Settings: Following are the most important settings. Others are optional.

  • Disable link prefetching: enabled
  • Strip metadata from allowed requests: enabled

Enabling the option to 'Block requests for missing resources' will break more websites and so the choice is yours.

Privacy-Oriented Origin Policy (POOP) by claustromaniac

Description: Helps to protect privacy by manipulating Cross-Origin Resource Sharing (CORS) requests.

Settings: I would recommend setting the 'Global mode' to 'aggressive' and enabling the 'Exclude root domain matches' and 'Spoof cross-origin Referer' options. You can also add the following to the 'Exclusions area: * *
* *

Skip Redirect by Sebastian Blask

Description: Skips link redirections such as used by Google, YouTube, AMO and many other websites, thus helping to prevent tracking. Redirects are intermediate links, such as '' or short links, that forward the browser to the final destination.

Settings: I would suggest enable the pop-up option so that you know when Skip Redirect skips a redirect, other than that the default settings are sufficient. You will likely have to whitelist sites that no longer work properly which Skip Redirect makes easy to do since you can copy the last skipped URL by right-clicking its toolbar icon and then adding that URL or domain to the blacklist.

uBlock Origin (uBO)

Description: uBlock Origin is an excellent ad/content blocker that can use the same filter lists as Adblock Plus as well as many more. Make sure you use the original uBlock Origin by Raymond Hill and no other. It is important that you enable advanced mode in uBO and learn how to use its dynamic filtering capabilities.

Settings: See the uBlock Origin Suggested Settings Guide. and use the settings in the 'Advanced guide settings' column.

Additional add-ons

For more possibilities regarding add-ons, see Firefox Extensions: My Picks.

Automatic add-on updates

The tl;dr version: Do NOT enable automatic add-on updates. The longer version...

Regarding automatic add-on updates, which is enabled by default in Firefox, this function is disabled in the 'arkenfox' user.js file and i would strongly suggest keeping it disabled. Automatic checking for updates is fine and this is enabled in the 'arkenfox' user.js, but we do not want Firefox to update add-ons without our explicit consent. The problem here is that developers may, at any time, and without notice, monetize their add-on or sell their work to an unethical 3rd party and this often results in compromising your privacy. Examples of some currently or formerly popular add-ons which contain(ed) such crapware are Abduction, a screen capture utility; Quick Locale Switcher, a language switcher; FasterFox Lite, a largely useless utility which claims to speed-up Firefox but doesn't; BlockSite, a content blocker; Stylish, a very popular utility for changing the appearance of websites, and many, many others. Not all of these extensions contained crapware when they were first introduced which is why i strongly suggest keeping automatic add-on updates disabled and carefully reviewing the change logs, permissions and privacy policies each time an update is available. The Extension source viewer add-on by Rob W. is a handy toolfor reviewing the source code of any add-on on AMO while visiting the site. For more about Firefox add-ons, see Firefox Extensions – My Picks.

Firefox configuration

This guide depends heavily on the 'arkenfox' user.js configuration file which alters hundreds of important Firefox preferences related to privacy and security, thus you need not worry about manually configuring anything from the Preferences menu of Firefox other than a search setting which we'll get to. If you choose to not use the 'arkenfox' user.js, then your job is likely to be considerably more difficult assuming your goals are similar. Still, you may find it helpful to refer to the 'arkenfox' project should you choose to start from scratch.

Search bar on navigation bar

I would suggest adding the search bar to the navigation bar and using it instead of the address bar for searching the web. Not only might you find it more convenient, but there are potential privacy concerns when searching from the address bar. To accomplish this, open the Firefox Preferences page, click the Search item on the left, then enable the option 'Add search bar in toolbar'.

Firefox profile in RAM

With the wide adoption of speedy Solid State Drives (SSDs), the concept of sticking the Firefox profile in RAM for performance reasons may seem obsolete, however there are still benefits to doing so.

If you don't want to disable disk caching, web storage and cookies globally, and thus break a lot of websites in the process, there will be substantial read and write activity for your storage media. Placing your Firefox profile in RAM will alleviate much of this, however doing so can be risky should a catastrophic failure occur, such as a power failure which could result in data loss or corruption. Fortunately there are ways to minimize this risk.

If you use Windows you're on your own since i don't, suffice to say that there exists Windows compatible software that can manage RAM disks and backup your profile to your storage media ('Bushdoctor' provides a method in a comment left on this article). Those using most any flavor of Linux have access to a very spiffy utility called Profile-sync-daemon (PSD) which is designed specifically for this task and it works with quite a few browsers. Check your package manager to see if it's available in your repository. To get PSD working, run man psd in a terminal or consult the guide on the Arch wiki. Setting it up was very easy in my case and it has worked flawlessly and transparently ever since.


Note that Firefox stores its web cache in a location other than the profile directory. On Linux you might find it in /home/[user]/.cache/mozilla/firefox/ . Normally you would have to deal with web cache separately if you wanted to store it in RAM also, however since disk caching is completely disabled in the 'arkenfox' user.js (cache is stored in memory) and the cache is dumped when you exit Firefox, you need not worry about it. If you're thinking it would be more efficient to keep the browser cache instead of having to re-download objects for the websites you visit frequently, you're right, however doing so can compromise your privacy. We won't exactly be dumping all of the browser cache either since we're using the LocalCDN add-on.

Configuration files

Keep the following hierarchy in mind as you read this section. When Firefox starts:

  1. prefs.js is read by Firefox
  2. user.js is read by Firefox - all preferences in the user.js file are copied to the prefs.js file and any preferences that are duplicated in both files are overridden by those in user.js - prefs.js is then used to generate what you see in about:config
  3. user-overrides.js is never read by Firefox but these preferences are appended to the 'arkenfox' user.js with a script (preferred) or by manual copying. If using the 'arkenfox' user.js then the user-overrides.js is the only file you should edit and it is where all your custom preferences should be placed. This may defy conventional knowledge, so let me be clear:

If you are going to use the 'arkenfox' user.js file then you should never edit it, (nor the prefs.js file that Firefox creates) nor should you change important settings from about:config unless you're only testing something. All of your custom preferences should be placed in your user-overrides.js file and then appended to the 'arkenfox' user.js using their updater script.

One reason for this is because the 'arkenfox' user.js file is quite a large and is updated frequently, so if you edit it and then update it, all your custom changes will be lost, whereas if you copy the preferences you want to alter from the 'arkenfox' user.js to your user-overrides.js and change the values there, then updating the 'arkenfox' user.js will be a lot less painful. On the other hand, should you choose to not use the 'arkenfox' user.js, then you should add your changes to your own user.js instead of using my user-overrides.js and you can ignore everything stated here about the user-overrides.js. Either way, never edit the prefs.js file directly or by way of about:config unless you're just testing.

If you do not have a general understanding of the the user.js file, you may want to read this on the 'arkenfox' wiki. You should also poke around elsewhere in the wiki for detailed information on using and maintaining their user.js file.

Obtaining and maintaining the user preferences files

In your profile folder, delete or rename your existing user.js file if you have one. You can transfer any needed settings later if they are not already covered in the 'arkenfox' one. Next, i might suggest considering my user-overrides.js file. Go to the at my repository and download the user-overrides.js file to your Firefox profile directory. The easiest way to get the file without messing up the formatting is to view the raw file, then press Ctrl+S to save it to your Firefox profile directory. Next, open the file for editing using your code editor and follow the instructions within.

After that we want the 'arkenfox' user.js from the arkenfox GitHub repository but you need not download it directly. Instead, grab their (Linux) or updater.bat (Windows) script by clicking the file name, then clicking the 'Raw' button in the new page and pressing Ctrl+S to save the file to your Firefox profile directory. Use the same method to get a copy of their (Linux) or prefsCleaner.bat (Windows) and place it in your Firefox profile directory. The prefsCleaner script will reset any depreciated, removed, or inactive preferences and it's important that you do this whenever you update the user.js. If you're running Linux, don't forget to make the files executable. Next, run the updater script in a terminal to fetch the 'arkenfox' user.js ( $ ./ ). The script will automatically append the contents of your user-overrides.js to the 'arkenfox' user.js it if it finds one.

At this point it is important to go through the entire 'arkenfox' user.js file and read all of the comments and review each of the settings to be sure everything is configured the way you want. As stated above, any preferences you want to change in the user.js file should be copied to your user-overrides.js file where you will then change their values. Note that if you ever add and then comment out or delete a custom preference in your user-overrides.js which is not contained in the 'arkenfox' user.js, and you have run Firefox after doing so, that setting will remain in the prefs.js file. The safest way to remove such preferences is to open about:config in Firefox and reset them.

Over time it is possible that your user-overrides.js file will contain preferences that are obsolete. The 'arkenfox' user.js file contains a list of some of these preferences in [SECTION 9999]: DEPRECATED / REMOVED / LEGACY / RENAMED and these preferences should be removed from your user-overrides.js file. One very tedious way to do this is to go through the list line by line and see if they are duplicated in your user-overrides.js. An easier way is to use the -c switch (documentation here) when you run the updater script which will output a 'diff' file containing the differences between the old user.js and the new one.

I suggest you run the updater script with the -c option (Linux only) every time you update the user.js file or make changes to the user-overrides.js file. This will create a "diff" file containing the differences between the old and current versions. You can read more about the updater script here and the cleaner script here.

Verifying the integrity of user.js

IT IS VITAL that you perform two integrity checks whenever the 'arkenfox' user.js file is updated or you have edited the user-overrides.js file if you're using one.

From the 'arkenfox' crew:

In FF60+, not all syntax errors cause parsing to abort i.e. reaching the last debug pref no longer necessarily means that all prefs have been applied. Check the console right after startup for any warnings/error messages related to non-applied prefs.

They reference the article, 'A New Preferences Parser for Firefox' if you're interested in knowing more.

To perform this check, you might want to disable your network connection so that, in the event there is a problem with a preference, Firefox cannot connect to the network and potentially allow data to flow in or out which you may have wanted to avoid. With that done, start Firefox and open the Browser Console from the Web Developer toolbox (Ctrl+Shift+J might work) and check for any preferences errors by pressing Ctrl+F to open the find dialog and entering 'pref' or 'user' and seeing if any errors point to preferences in your user.js file (other errors and warnings can usually be ignored).

Now we will further check the integrity of the user.js file and, by extension, also the user-overrides.js file since the content of the latter was copied to the end of former with the updater script.

You may have noticed a bunch of unusual looking _user.js.parrot preferences in the 'arkenfox' user.js as well as in my user-overrides.js if you're using it. These are used find the approximate location of any syntax errors. When you run Firefox for the first time after updating the user.js or making changes to your user-overrides.js, check the value of the troubleshooting preference by entering about:config in the address bar and searching for the _user.js.parrot preference (it may be the first one listed without having to search). The value should match the very last _user.js.parrot preference value in your user-overrides.js or, if you are not using a user-overrides.js, then it should be the last value in the 'arkenfox' user.js.

If you're using only the 'arkenfox' user.js, the value should be, " SUCCESS: No no he's not dead, he's, he's restin'! ".

If you're also using my user-overrides.js, the value should be "SUCCESS! USER-OVERRIDES SETTINGS LOADED" .

If the value for the troubleshooting preference is not what you expect, then you can use it to quickly determine in which section of the user.js or user-overrides.js the syntax error lies. While it cannot narrow down the problem to a specific preference or line number, at least you will know where to begin looking.

Updating the user.js and user-overrides.js files

To update the 'arkenfox' user.js file, run the updater script (you can add the the -c switch as explained earlier if you're running a Linux OS). To update my personal user-overrides.js file, just copy the contents of the new version to your user-overrides.js, then run the updater script. Lastly, always run the 'arkenfox' prefsCleaner script with Firefox closed whenever you update the user.js or my user-overrides.js.

The 'arkenfox' user.js is updated frequently and so you'll need to check for updates regularly. There's two ways you can check for updates if you're running Linux and one if you're running Windows, however there's only one (easy) way to actually update the user.js and that's by using the 'arkenfox' updater script.

user.js-notify script message (Linux)If you're using a Linux-based OS you can use my script to be automatically notified via a desktop notification when:

  • the 'arkenfox' user.js is updated
  • my user-overrides.js is updated
  • this guide is updated

You can add the script to your startup programs so it runs each time you log-on to your desktop, or run it automatically some other way. Instructions for implementing the script are contained within the script. Open the file with a code/text editor to read the instructions and edit the options.

To check for a new user.js if you're running Windows, or to actually update the file, exit Firefox and run the 'arkenfox' updater script. If you're running Windows, or if you're running Linux and don't wish to use my script, you should run the updater script every week or so in order to check for a new version. You always want the user.js version that corresponds to the major version of Firefox, so if the updater script says Available online: * version 80-alpha and you're running Firefox version 79.0.1, you'll want to cancel the update because 80 doesn't equal 79.

Each time you run the updater script, be sure to follow it up by running the prefsCleaner script with Firefox closed.

To be notified of updates to my user-overrides.js file you can subscribe to the news feed for the Firefox category or watch the front page feed.

DNS over HTTPS (DoH)

In the alleged interest of privacy, Firefox has added code which allows to route all DNS look-ups over HTTPS to a resolver of your choice. Typically DNS queries are routed through your ISP, so while they cannot view your traffic as long as it's encrypted (HTTPS), they can see what websites you visit and this is a serious privacy concern. There are several ways to mitigate this, one of them being to use a VPN that provides DNS services. Another is to enable DoH within Firefox, however this will only protect your browser and not any other programs on your system that connect to the internet. Moreover, there seems to be a lot of controversy regarding DoH, so before you enable this setting you might want to watch the video, Paul Vixie talks about DNS over HTTPS, and read this on Wikipedia, and also the article, Mozilla is becoming evil.

Part of the DoH system in Firefox can be controlled with the preference, network.trr.mode , however it is easier to simply use the Preferences UI to do so (Preferences > General > Network Settings > Connection Settings). The default DNS resolver is Cloudflare, but given what i have read about this company, i would highly suggest not using it. You might want to do some research and locate a privacy-centric DNS resolver to use for DoH should you decide to enable DoH.

If you decide to use my user-overrides.js preferences file, note that it disables DoH by setting network.trr.mode to '5' (i use a VPN that provides DNS). You will need to change that if you want to enable DoH.


Thanks to 'AHappyUser' for reminding me about the policies.json configuration file which can be used to control how Firefox behaves, particularly in enterprise environments. 'AHappyUser' linked to the Controlling Firefox section of the article, Mozilla is becoming evil - be careful with Firefox, which provides a few examples of what can be done with the policies.json file. Note that all of the examples given can be controlled via preferences in your user.js file so there is no need to create the policies.json file, however i mention it because some folks may find it useful. For more information regarding what can and cannot be done with policies.json, see the Mozilla repository on GitHub.

Persistent web storage (cookies, etc.)

A problem that will likely creep up at some point is a website not saving settings across browser sessions that you wanted to save, such search engine settings for example (If you want to learn more about alternative search engines, read Alternative Search Engines That Respect Your Privacy). To save this data you will need to edit the permissions for the domain and there's two easy ways to access them; you can click the padlock icon in the address bar, then the right-facing arrow, then "More information", or simply hit Ctrl + I. In the window that opens, click the "Permissions" icon and scroll down until you see the "Set Cookies" item. Finally, deselect the "Use Default" preference and select the "Allow" preference. Firefox will now save the website data for the domain you're visiting even after it is restarted.

THE END (lie)

While there are many more things you could do if you're really concerned about protecting your privacy and browser integrity, i hope this guide has been of some use to the technically adept novice or intermediate web surfer at which it is aimed. Understand however that there are threats present in almost all computers which users have little or no control over regardless of what software or operating system is used. Such threats include the Unified Extensible Firmware Interface (UEFI) which has all but replaced the Basic Input/Output System (BIOS) for booting the computer. Intel's Management Engine (IME) and AMD's Secure Processor (SP) / Platform Security Processor (PSP) present a massive threat to security and privacy for virtually everyone using any Intel or AMD powered device.

Lastly, if you are using a proprietary operating system, be it Windows or any other, it is absolutely crucial that you move to a more secure, open source OS such as Linux. The importance of doing so cannot be overstated in my opinion. For more information, read the free book, Free Yourself from Microsoft and the NSA.

I welcome any questions or comments you may have, just please leave them in the comment section so others can benefit (you need not be logged in).

IMPORTANT: If you incorporate suggestions made in this guide, please subscribe to the Firefox category on the subscription page. This article is updated fairly often and it's the best way to stay informed.


I must thank all of the dedicated and skilled people who created, maintain and contribute to the arkenfox/user.js repository, especially Thorin-Oakenpants (aka, 'pants') and earthlng. This guide would never have been as comprehensive as it is without the benefit of that bunch of misfits :) Also i'd like to thank the many people who make privacytoolsIO possible. Their website is an excellent resource for those looking to protect their privacy and security.

Also i thank the many people who have left comments here, many of which have been very helpful in correcting, maintaining and improving this guide.


Further reading on this website

The 'arkenfox' repository on GitHub

Everything else

Revision history

Click to expand...


  • removed CSS Exfil Protection


  • removed Clear URLs add-on - it's unnecessary given the 'arkenfox' user.js and updated suggested settings for uBlock Origin


  • removed CanvasBlocker
  • removed Cookie AutoDelete (rather obsolete with dFPI and v96 of arkenfox user.js, plus due to delayed cleaning it doesn't offer the level of protection we want)
  • removed section on HSTS tracking (largely if not entirely obsolete)
  • added 'Persistent web storage' section


  • changed user-overrides.js successful loading parrot from "SUCCESS! USER SETTINGS LOADED" to "SUCCESS! USER-OVERRIDES SETTINGS LOADED"


  • removed all references to uMatrix since it's no longer developed and is becoming less effective at time ticks on - uM users are advised to use uBO in advanced mode instead
  • corrected some information and made some minor changes to language


  • changed wording for the suggested uMatrix settings in the 'Settings, Convenience' section


  • trivial edit


  • updated info for the privacy settings for uMatrix
  • removed HTTPZ add-on and associated info - no longer needed since Firefox v83 as long as is enabled
  • added a note in ClearURLs settings regarding hyperlink auditing
  • minor clarifications, edits


  • minor edits and clarifications in the 'Terminology' section


  • changed recommendation for the use of CAD (i DO recommend it) - see sections 'Cookie AutoDelete by CAD Team' and 'Cookie AutoDelete (CAD) usage'
  • minor edits


  • added info about the script


  • reversed the order of this revision history so the latest changes are at the top - big sloppy kiss to 'Anon' for helping with that


  • added notes to CanvasBlocker, Cookie AutoDelete and LocalCDN stating that they are optional - the reason they are optional are because of settings in the 'arkenfox' user.js, particularly privacy.firstparty.isolate , privacy.resistFingerprinting and the clearing of storage on browser exit - many readers may see this decision as strange, in which case i'd recommend reading the Questions regarding compartmentalization, extensions and uniqueness thread in the 'arkenfox' user.js issues
  • for uMatrix several suggested settings in the "Settings, Privacy" section were removed, these being:
    • Delete blocked cookies
    • Delete non-blocked session cookies minutes after the last time they have been used
    • Delete local storage content set by blocked hostnames
    • Clear browser cache every minutes
    • Strict HTTPS: forbid mixed content
  • added info in the 'Cookie AutoDelete by CAD Team' section instructing how to save storage for a website if not using CAD


  • added info about how to automatically be notified when a new version of the 'arkenfox' user.js is available (Linux only) in the 'Updating the user.js and user-overrides.js files' section
  • minor edits


  • replaced Site Bleacher with Cookie AutoDelete (CAD) - search for "Cookie AutoDelete" to see the edited content
  • minor edits


  • added info about importing rules from LocalCDN to uMatrix - see the paragraph beginning with "If you're using the LocalCDN add-on"
  • added link to article, How to setup uMatrix [a beginners guide] | Step-by-step with pictures
  • added info about having to reload (vs. refresh) a page when allowing frames in uMatrix - see paragraph beginning with "Note that any time you allow frames"


  • minor edit


  • minor edit


  • added a bit more info to the 'THE END' section regarding AMD and Intel backdoors


  • slight change to the uMatrix section regarding the spoof noscript option


  • added information about the uMatrix option 'Spoof <noscript> tags when 1st-party scripts are blocked' and how this can break the displaying of images when the option is disabled.


  • added the video, Prof Shoshana Zuboff on surveillance capitalism



  • added info to the uMatrix usage section about solving a problem regarding uMatrix and file downloads
  • very minor edits


  • removed info about CSP (Content Security Policy) issue since this is fixed in Firefox v77
  • adjusted Canvas Blocker settings to accommodate for absence of CSP issue
  • added the policies.json section
  • added section 'DNS over HTTPS (DoH)'


  • minor clarifications/edits


  • minor clarification in the uMatrix section regarding LocalCDN rules for uBlock Origin


  • removed invalid uM directive: no-workers: 1st-party false - thanks to 'theltalpha' for pointing this out


  • replaced remaining references to Decentraleyes with LocalCDN
  • updated the URL for the uBlock Origin Suggested Settings Guide


  • updated uMatrix settings and information regarding web/service workers (added a directive to allow 1st part workers by default for less breakage)


  • slight edits to the 'Verifying the integrity of user.js' for clarification


  • added the 'A note regarding user comments' section


  • swapped out Decentraleyes for LocalCDN - thanks to commenter 'theltalpha' for reminding me about this


  • removed ETag Stoppa since eTag filtering is now handled by ClearURLs
  • added detail regarding ClearURLs settings


  • minor updates/clarifications


  • minor edits to uBlock, uMatrix and HTTPZ settings


  • added ETag Stoppa
  • added more info regarding browser fingerprinting


  • minor edits


  • updated info for CanvasBlocker


  • minor edit


  • added a note to Canvas Blocker marking it as optional
  • added a note regarding the no-workers: * true setting in uMatrix


  • stuck the uBlock config stuff on its own page


  • moved my user-overrides.js from GitLab to Codeberg code repository


  • updated setup instructions for HTTPZ
  • minor edits


  • very minor edit


  • added note that this guide is not intended to be use with the Tor browser
  • minor edits


  • added a note about enabling the search bar on the navigation bar
  • minor edits


  • moved my Mozilla rant to a separate page
  • added a cryptominer block filter URL to uBlock


  • removed mention of LibreFox (project is currently stalled due to legal nonsense)
  • minor corrections, clarifications and edits



  • minor edits


  • minor edits


  • several clarifications and minor edits


  • removed info about manually cleaning the user-overrides.js file in favor of using the -c switch when running the updater.js/updater.bat script
  • added Site Bleacher to list of required add-ons
  • removed all info regarding containers as well as the Temporary Containers and Firefox Multi-Account Containers add-ons - i prefer to enable privacy.firstparty.isolate (the default in the 'arkenfox' user.js) in combination with Site Bleacher (far less headaches)
  • replaced Neat URL with ClearURLs - while the former is a good extension, i think the latter is even better
  • replaced Smart HTTPS with HTTPZ
  • moved all add-on settings info to the required add-ons section
  • uBlock: added info for globally blocking 3rd party fonts while allowing 1st party fonts
  • misc. edits


  • added instructions for cleaning user-overrides.js of obsolete preferences
  • minor edits


  • added a link to a comment by 'Bushdoctor' who was kind enough to provide information about loading Firefox profiles in RAM for Windows users


  • updated info on HSTS tracking
  • updated info regarding downloading my user-overrides.js file


  • minor polishing


  • clarify information regarding the downloading of the configuration files thanks to a commenter
  • updated user-overrides.js
  • fix minor typo


  • minor edit


  • added some more info regarding HSTS tracking and the SiteSecurityServiceState.txt file based on user feedback - it appears some AV's might have a problem if this file is set to read only
  • added a new resources section specific to the 'arkenfox/user.js' GitHub repo
  • added Temporary Containers (TC) add-on and associated info - this results in several major changes throughout the guide
  • added Firefox Multi-Account Containers add-on and associated info - this is used in conjunction with the TC add-on
  • added 'Using containers' section
  • removed Canvas Blocker add-on - not needed with TC
  • removed Restrict to Domain add-on - not needed with TC
  • removed Don't touch my tabs! add-on - (probably) not needed with TC
  • removed Header Editor - not needed for what we were using it for since the function is handled by TC
  • re-added privacy.firstparty.isolate = false to user-overrides.js
  • edited some uMatrix info regarding its privacy settings to reflect changes as a result of the TC add-on
  • added more info about importing rule-sets for uMatrix
  • moved Smart HTTPS add-on to the required section
  • moved Skip Redirect add-on to the required section
  • removed the suggested add-ons section
  • corrected mistakes and updated info in the section regarding integrity checking of the user.js/user-overrides.js files
  • reworked and updated the entire user-overrides.js file
  • removed mention of the template user-overrides.js file and associated download link - user should use the one provided in my GitLab repo
  • several minor edits/clarifications


  • add notice about newsletter subscribing
  • corrected advice regarding spoofing the referrer which was suggested for both POOP and uM (now it's enabled in uM only)
  • dumped Cookie AutoDelete add-on - not needed when using uM and First Party Isolation, nor are any of these storage cleaning add-ons able to delete IndexedDB storage due to a shortcoming in the WebExt API, which is another reason to enable FPI
  • removed privacy.firstparty.isolate = false in user-overrides.js in order to enable First Party Isolation
  • added Restrict to Domain add-on to toggle privacy.firstparty.isolate (FPI) via toolbar button
  • removed the list of optional add-ons (NoScript and Smart Referrer)
  • minor edits
  • coming up: looks like i may be recommending to disable FPI in the very near future and use the Temporary Containers add-on instead - i'm playing with it now


  • minor clarifications


  • added POOP as a required add-on and accompanying configuration information
  • configuration information for Neat URL was located in the wrong section
  • minor polishing


  • clarified much information regarding the user.js files as well as other parts
  • added more info about browser fingerprinting
  • added more detail regarding system add-ons
  • added a user-overrides.js template
  • updated Header Editor rules download
  • added several more 3rd party resources
  • misc. minor edits


  • added more info to the uMatrix section, particularly about indexedDB storage
  • minor edits


  • added info about HSTS tracking
  • minor edits


  • added info about using the user created rule sets for uMatrix, as well correcting some mistakes and clarifying other uM info
  • polishing


  • add Cookie AutoDelete as a highly recommended add-on and updated configuration information for uMatrix to allow 1st party cookies by default
  • removed information about the Forget Me Not add-on
  • added information about First Party Isolation
  • added rule to uM to prevent web workers
  • added information about the uBO and uM logging functions
  • corrected some mistakes
  • polishing


  • added uMatrix to the add-on pile again
  • added the uMatrix sections of this document
  • removed info about running uBlock in advanced mode since we're using uMatrix for dynamic filtering instead
  • several minor edits
  • polishing


  • lots of clarifications and polishing, added several resources


  • added the section 'Firefox profile in RAM'
  • misc. other minor edits


  • rewrote most of this guide, so if you read it before, read it again :)


  • removed cryptocurrency miner section
  • removed information about the OpenH264 Video Codec plug-in since it seems Firefox is no longer shipping it, at least not on Linux
  • removed the Load from Cache add-on
  • removed some information about uMatrix since uBlock Origin covers most everything uMatrix does and is better suited for removing advertisements, plus it's a much more active project.
  • updated some information
  • note that many more updates will occur in the next days, so i would suggest waiting until they are published before following this guide


  • minor edits


  • added a link to my post about the Firefox add-on, Looking Glass
  • misc. minor edits


  • added to the list of recommended add-ons
  • updated some content to reflect the current state of Firefox and WebExtensions
  • misc. minor edits


  • added more info about IndexDB storage in the "Terminology" and "uMatrix configuration" sections.


  • added section "A special note about cryptocurrency miners"


  • i didn't keep track of all the changes and many were made - you'll have to re-read the guide :)


  • added some add-ons to the recommended section
  • misc. minor edits


  • rewrote and updated much of the content pertaining to uMatrix
  • added section "Removing system add-ons"
  • added section "Sanitizing the default search engine plugins"


  • deleted the GitHub repository which i forked from Pants' 'arkenfox' repository and created a new repository which does not include his code
  • some changes to user.js
  • some major editing of this document mostly in regard to the creation and changes of the GitHub repositories


  • updated user.js to version 51r2 - see the GitHub page for the change-log
  • updated info here regarding the user custom preferences section of user.js


  • published my user.js on GitHub which was forked from Pants' code
  • removed my user.js code from this page and linked to it on the GitHub page instead
  • changed my versioning scheme to match Pants' where the user.js version coincides with the version of Firefox it was developed for, so v51r1 would equate to version 51.x of Firefox and the r1 signifies the revision, in this case the first revision
  • updated user.js to include v51 of Pants' config - no preference changes so far as i know, just added/removed/changed comments
  • updated text in user.js section to account for the new changes
  • changes to comments and troubleshooting preference names and values, other minor changes


  • switched to using Pants' config v0.11 and mostly just appending my settings to the end of his - because this is a major update, no history of changes to individual preferences will be published


  • removed Extension Defender from the list of recommended add-ons since it's home page is gone and the code hasn't been updated in two years
  • updated user.js file


  • removed duplicate preferences in use.js file (see change-log in the file for details)


  • changed the name of the troubleshooting/bogus preference to and added values to indicate the point at which the file stopped loading - a huge thanks to commenter 'Pants' for suggesting the troubleshooting preference and also for suggesting a far better way of implementing it than what i had done (by the way, 'Pants' is the author of the user.js config file used in the 'arkenfox' article, A comprehensive list of Firefox privacy and security settings by Martin Brinkmann, so i'm very glad to have his input here)


  • corrected 'plugin.scan.*' values to be strings
  • added bogus preferences in the user.js file at the end of each section for troubleshooting potential loading problems


  • added some basic information for configuring the Clean Links add-on


  • set 'browser.fixup.hide_user_pass' back to its default value
  • added 'network.http.redirection-limit'


  • corrected an error with pref 'layout.css.devPixelsPerPx' where the value was an integer instead of a string - this caused all prefs following it to be ignored


  • updated user.js file
  • minor grammar/spelling corrections


  • updated user.js file


  • updated guide information
  • updated user.js file and added a revision history to the file


  • updated user.js file contents


  • updated user.js file contents


  • updated user.js file
  • removed pcxFirefox as a suggested 3rd party build since i had display corruption issues with it


  • Minor edits for uMatrix usage text


  • added more info for uMatrix and IP Config test results
  • updated user.js file contents
  • various other edits


  • removed HTTP UserAgent cleaner since it is no longer being developed
  • removed Self Destructing Cookies add-on since its functionality can be handled by uMatrix
  • added uMatrix


  • updated uBlock settings to match the current development version (
  • misc. minor updates


  • switched to Raymond Hill's version of uBlock
  • updated uBlock filter information
  • added Fetch information for new version of HTTP UserAgent cleaner
  • updated user.js file contents
  • misc. minor updates


  • added information for securing DNS traffic
  • misc. minor updates


  • minor updates to user.js file contents


  • updated user.js file contents
  • updated a few settings recommendations for HTTP UserAgent cleaner


  • updated list of recommended filters for uBlock
  • updated user.js file contents


  • added Pure URL as a suggested add-on
  • updated contents of the user.js file
  • added and edited some information for HTTP UserAgent cleaner
  • added more resources in the References section


  • updated HTTP UserAgent cleaner information to match changes in version


  • updated the information for the Fonts filter on the HTTP tab of HTTP UserAgent cleaner


  • updated information for HTTP UserAgent cleaner, including adding descriptions for the newly added features, Canvas and Fonts on the HTTP tab
  • updated the user.js file
  • updated some definitions of terms used in this document
  • added some more resources


  • updated some HTTP UserAgent cleaner information
  • deleted information for 2 bugs regarding the X-Forward-For setting for HTTP UserAgent cleaner since they were not bugs
  • misc. other minor changes


  • updated information for HTTP UserAgent cleaner
  • updated user.js file
  • minor updates to uBlock information
  • misc. other minor changes


  • updated HTTP UserAgent cleaner information
  • for HTTP UserAgent cleaner settings, the suggested settings were split into Suggested global setting for casual browsing and Suggested global setting for best protection.


  • updated and added more information for uBlock
  • updated one HTTP UserAgent cleaner screen-shot
  • misc. other corrections/updates/edits


  • updated user.js file
  • switched uBlock versions since a new fork was created
  • updated uBlock images and documentation
  • added a "Current notices" section
  • misc. other corrections/updates/edits


  • updated user.js file
  • several other small updates and a few corrections


  • removed all Shim Storage add-on information since this functionality is duplicated in HTTP UserAgent cleaner.
  • almost all of the documentation for HTTP UserAgent cleaner was heavily revised.
  • various other edits and corrections.


  • first publishing


Note that both reader and my comments, while they may have been accurate at the time, might be inaccurate today. This is a highly dynamic environment so please verify the accuracy of comment content should you wish to utilize it. Failing that, ask me and i'll give it a crack.

486 thoughts on “Firefox Configuration Guide for Privacy Freaks and Performance Buffs”

  1. 1) I can not understand how do i install it for linux?

    2)HTTPZ is better than HTTPS Everywhere?you only need one of the two?

    3)when install canvas blocker in the panopticlick result fingerprinting is partial and without canvas blocker add on my result fingerprinting are : has a non-unique fingerprint

    1. re: – you’ll need to re-download the script because i changed the name of it (it’s now

      re-read the instructions here

      how you enable the script to run automatically is up to you

      using this script is not mandatory, but if you don’t use it, just remember to manually check for user.js updates using the ‘arkenfox’ updater script

      re: HTTPZ & HTTPS Everywhere: they both have advantages – personally i much prefer HTTPZ

      re: Canvas Blocker: don’t worry about the result you get from panopticlick – for more on this, read through the ‘arkenfox’ user.js issues here

      personally i no longer use Canvas Blocker since Firefox covers *most* of what CB does (assuming you’re using the ‘arkenfox’ user.js)

      1. Thank you for the answer and the very good job you do for the privacy.where can i watch if a new update comes out?and if it comes out I just pull the user.js file into the mozilla root folder?what i have done so far is to download ghacks user.js to open the folder and put the user.js file in the root profile mozilla folder.

        and I have also put extensions like ublock origin,uMatrix,HTTPS Everywhere,Decentraleues,cookie autodelete,css exfil protection,LocalCdn,privacy oriented,skip redirect,Clear Urls, along with the settings you suggest.
        but i can not watch video on youtube,or,xhamster,or pornhum e.t.c. while I allow various things from umatrix I still can not watch videos from these sites

        1. hi Justin – couple things right off the top…

          * why are you using both LocalCDN and Decentraleyes?
          * the ‘ghacks’ project name is no more – the new name is ‘arkenfox

          > where can i watch if a new update comes out?

          if you’re using a Linux OS, see this – if not, it is explained in this guide how to check for updates to the ‘arkenfox’ user.js using their updater script

          > and if it comes out I just pull the user.js file into the mozilla root folder?

          put the updater script in your Firefox profile folder (where prefs.js and user.js are) and run it

          > but i can not watch video on …

          it seems like this guide might be a bit too technical for you – you may want to follow the ‘dummy’ guide instead

          if you want to stick with this guide, you’ll need to read the uMatrix and uBlock wiki – links are in the guide

          1. Thank you very much for the answers and sorry if I stun you.

            I do not understand if I need to create a new profile or put the files directly in the default folder?

            to me from the beginning had two profiles: Profile: default-release and Profile: default.I put the files in the main profile Profile: default-release
            now i have to do the process again because like you told me the new version is arkenfox .

            and I’m confused about user-overrides.js. arkenfox does not include them all;

            1. you never need to create a new profile to put a new version of the ‘arkenfox’ user.js in – you should be using the updater script in the arkenfox repo to update the user.js

              user-overrides.js is where your custom settings go – it does not exist by default – i offer my personal user-overrides.js for people to use if they want, but you can create your own as well – the content of this file will be appended to the user.js using the updater script

              ALL custom setting should go in user-overrides, such as any settings in user.js or prefs.js that you want to change

    1. Site Bleacher cannot clean indexedDB storage per-host – it can only dump iDB globally (for all hosts), so this can potentially break sites – also Site Bleacher was originally coded for Chromium, not Firefox, and i don’t think the developer is very familiar with the Firefox extension API, so i have a lot more faith in CAD

  2. I found some interesting extensions on the arkenfox userjs wiki that I wanted to know your opinion of. Request Control and Header Editor both appear to much of the same thing; combine the features of Httpz, Redirector and ClearURLs. Both are a lot more complicated though. Next is Smart Referer, which controls referer headers much like POOP and uMatrix. Not sure if it’s better at it, hence why I wanted your thoughts.
    I also wanted to mention a few things about the user-overrides.js. The overrides script sets container tabs to off by default but Canvas Blocker requires it to be enabled and overrides the setting making it redundant. Hiding the UI is probably more than enough. It would probably also be useful to include the firstparty.isolate setting (set to true by default of course) for those that would rather disable it for use with Temporary Containers with Multi-Account Containers. I’ve been playing around with these two lately and, while can’t say they’re better than first party isolate with site bleacher, can say they have their own merits. Finally, while a VPN is definitely better than any of the secure dns crap, privacytools io has a page for secure dns responders; it might be worth while to include blank versions of the lines “network.trr.uri” and “network.trr.custom_uri” with a link to the page in the comments as to prevent users who do decide to enable it from completely screwing themselves with cloudflare’s service.
    Going back to Canvas Blocker, is it ok to use with firefox’s builtin finger print protection?

    1. Request Control and Header Editor i really can’t comment on – i don’t use either – it’s one of those deals where, if you think you need it, use it, else don’t complicate things because more “things” means more breakage

      i wouldn’t compare ClearURLs with Request Control – there’s a lot going on with ClearURLs and it pulls its filters from the developers repo, and there’s a lot of them

      i don’t think Smart Referer is needed if you enable the option ‘Spoof HTTP referrer string of third-party requests’ in uMatrix – if you don’t use uM, then yeah, i’d probably go with Smart Referer – i don’t know if it works better or not

      re: Canvas Blocker – i personally don’t use it since Firefox now handles most of what CB does (not all) and i just found that it requires too much attention and it’s yet another thing to troubleshoot when something breaks

      > Going back to Canvas Blocker, is it ok to use with firefox’s builtin finger print protection?

      yes, far as i know – CB detects if RFP is enabled and acts accordingly (gets out of the way where necessary) – the dev mentions this somewhere

      > It would probably also be useful to include the firstparty.isolate setting

      if you mean in my overrides, yeah, i agree – i’ll do that (actually i just did)

      re: Site Bleacher – you can drop that if you want in favor of Cookie AutoDelete – it handles indexedDB storage now, per-host, automatically (cleans when you close the last tab for that host)

      i’ll look in to the DNS stuff

      thanks much for bringing these things up – it’s good that you guys keep an eye on me o_0

  3. Excellent article as usual! Just curious, can you give a complete list of the addons you use currently? (Including non-privacy extensions.) I’m curious as to whether you use a password manager. Also any thoughts on ungoogled Chromium? It’s supposedly more secure than Firefox.

    1. the add-ons i use are listed here

      i use Firefox’s built-in password manager – i’m not sure that’s the best idea because i never researched whether it’s secure

      as for ungoogled Chromium, is it more secure than Firefox after implementing the ‘arkenfox’ user.js? i don’t know, but i know there are certain things that are done differently in Chromium that make it less attractive from a privacy standpoint, though at the moment i don’t recall what they are – also the Tor project uses Firefox as a base for their browser, so i think that says something – then there’s the ‘arkenfox’ user.js project which has some very knowledgeable people on board with connections to Mozilla and Tor

      1. Oh yeah, I read your addons article, I just didn’t know you used all of those. Good points. I need to mess around with user.js a bit. Check out a guy on reddit by the username “cn3m”. He’s quite knowledgable about security and uses UG Chromium. Also, your articles introduced me to HTTPZ which is a hidden gem. Thanks for the reply!

        1. Firefox has a preference for forcing https, unfortunately there is no fallback to http, thus the need for HTTPZ (or something like it) – i happen to be a bit familiar with the developer who is a great guy and i prefer the why it works over the others

    1. as much as my guides are for others, for sanity’s sake i keep them current with the version of Firefox i’m running – maintaining them for older versions would just be a big fat headache

      i suspect you already know this, but the CSP issue is resolved in 77

    1. CB informs you what it blocked, so you’ll have to go by that – personally i quit using it and it will hopefully be removed from my guides soon since the Firefox devs have been making progress with canvas anti-fingerprinting (it’s almost there now)

    1. i thank you much for sharing that since this information may be valuable to many users – and i will credit you and add a note about this in the guide – however regarding DoH, it appears it can be disabled in the Firefox preferences UI: Preferences > General > Network Settings > Enable DNS over HTTPS – you can also select a provider there, or specify a custom one – you can also use the preference network.trr.mode to control DoH, which, for those using my user-overrides.js, is already disabled

      1. Uncomfortable with that option since it is easy for less technical users to bypass all effort (like family filter, no logging DNS) with a single click. The lock option within admin folder (/usr/(local)/lib/firefox/distribution) setting ensures a safety net by completely taking it out of picture.

        Credit or no credit – the yeomen service feels satisfactory! Thank you for your consideration.

  4. Thanks for the guide, loving it so far. Just one question; I am using Bitwarden and it keeps logging me out. Didn’t used to happen on my older firefox setup. Is there anything I need to change to stop it from doing so?

  5. 12bytes,

    1. Can you please provide an example on how to do this for Skip Redirect extension? Whitelist and blacklist are confusing terms for end-users.
    2. The uBlock Origin Settings page needs to have ‘My rules’ tab setting updated similar to one here for LocalCDN.
    3. CanvasBlocker now has default setup options of template that might be interesting to add to in the article.

    A Request: Any resources to make the arkenfox user.js scripts be shellcheck compliant (remove bashisms)?

    Thanks to all you do and a shoutout to the arkenfox team as well.

    1. #1 – for Skip Redirect, enable the following options:

      * Skip all redirects except for URLs matching any of the lines in the blacklist.
      * Skip redirects for URLs with the same public domain
      * Enable popup

      now when a redirect does occur, but you didn’t want it to, right click on the toolbar icon (i put the icon in the overflow menu) and click the ‘Copy last skipped URL’ menu item, then click the icon again to open the settings and add the domain to the blacklist

      what you add to the blacklist is up to you – in the case of, you can add just that, or you can add if you want to skip redirects only for that subdomain, or you can add to skip redirects for a particular path

      here are some examples…

      #2 – not sure i understand your comment, but if you mean that the LocalCDN domain list needs to be added to uBO, that is true only if you’re using uBO in advanced mode (you enable dynamic filtering)

      #3 – i haven’t played with the templates yet – thanks for reminding me about that

      does shellcheck do JS? i thought it was only for shell scripts – also that’s something i would not worry about since you should never be editing user.js

      1. For #2, meant to say the reference is still for Decentraleyes in the article which has been retired in favor of LocalCDN.

        Shellcheck checks for POSIX-compliance. The shebang right now used by the arkenfox scripts ( and works only with bash (to be fair: they state that outright in the github page). Making it shell-agnostic (the shebang to #/bin/sh) and removing bashisms (like double brackets, [[]]) would make it portable across portable machines (containers, VMs, etc). I spent half an afternoon porting it to ksh (pdksh specifically in the hopes of sharing it here) but am not an expert and failed at a little more than 70% through. I will give it a shot sometime else and will update here, if you don’t mind i.e.

        1. re: #2 – ok, i gotchya now – i updated the page accordingly and thanks for pointing that out

          re: shellcheck – i thought you meant you wanted to run it on the user.js – i misunderstood

          i agree that the updater script could be better and i would highly suggest you bring this up, as well as the changes you’ve made, on the arkenfox repo – i have nothing to do with the updater script nor am i an accomplished shell scripter

            1. your changes worked for me in a bash shell – i just saw 1 very minor shellcheck issue…

              In line 337:
              if [ ! -z "$diff" ]; then
              ^-- SC2236: Use -n instead of ! -z.

              and a small script issue…

              sed: character class syntax is [[:space:]], not [:space:]

              1. Not mine Sir, I just dug around from the link you provided on the closed github issues. Don’t see much activity with the user on this repo or github. I will be testing on the *BSD though and will report when done.

                1. The arkenfox script checks for update when first run which will override any of the changes unless checked in, i.e., the shebang of /bin/sh will be replaced by /bin/bash. The above-mentioned user’s script works alright.

    1. Hallo! In order to obtain the settings in your linked screenshot, you would have to add these lines to the “My Overrides” section in the user-overrides.js:

      user_pref(“network.cookie.cookieBehavior”, 4);
      user_pref(“privacy.trackingprotection.enabled”, true);
      user_pref(“privacy.trackingprotection.socialtracking.enabled”, true);

      1. Hello,
        Thank you very much! It worked. I added:

        user_pref(“network.cookie.cookieBehavior”, 4);
        user_pref(“privacy.trackingprotection.socialtracking.enabled”, true);

        (I already had user_pref(“privacy.trackingprotection.enabled”, true); )

        then ran ./ & ./

        Everything is fine.

    1. thanks for informing me of this
      i used to test this since workers must be enabled for highlighting of the test string to work and i verified that the rule works … i just now re-tested this and it does NOT work – so i obviously messed something up

      i’ll update the info in the guide accordingly – thanks again

  6. Hi,
    I did a fresh Firefox install recently; been following this guide, but I’ve just noticed that with your suggested extensions (and related settings, except Matrix, which I’m not running) Element Picker and Element Zapper in uBlock don’t work. Any idea what extension might have caused this?
    Best regards.

    1. in the advanced config guide i recommend running uBlock with its advanced mode disabled and using uMatrix for dynamic filtering – when advanced mode is disabled, the element picker does not function – if you don’t want to use uMatrix, then i’d suggest enabling advanced mode in uBO, but make sure you read the uBO wiki

      1. Thing is, I have advanced mode turned on, but that still doesn’t allow me to use the element picker fucntion, which is why I’ve asked here in the first place.

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