Configuring Firefox

What is this?

It's a text file you can put on your computer that turns off some of the dumb shit Firefox does, like phoning home. It also changes your search engine and installs some useful browser extensions. I consider it the bare minimum necessary to configure Firefox so that it behaves in a reasonable manner.

Where's the file?

Right here.

Where do I put it?

Depends on your operating system:

Linux: /etc/firefox/policies/
Flatpak: $HOME/.local/share/flatpak/extension/org.mozilla.firefox.systemconfig/x86_64/stable/policies/ Note the bolded 'x86_64' and 'stable' -- you'll have to guess what those are if you're running a different architecture or branch. Good luck, and while you're trying to figure it out, ask yourself if this stupid package manager is worth it.
FreeBSD or OpenBSD: /usr/local/lib/firefox/distribution/
OpenBSD (Firefox ESR): /usr/local/lib/firefox-esr/distribution/
NetBSD (via pkgin): /usr/pkg/lib/firefox/distribution/
MacO's: Firefox.app/Contents/Resources/distribution/
Windows: stop using Windows. Apparently you have to find firefox.exe and make a distribution directory there and put the file there? Toy OS. Garbage.

Anything else I should do?

Open a new tab and type about:config into the URL bar. Click I accept the risk. Then, Paste beacon.enabled into the search box. Make sure the value is false. This turns off a tracking tool that the policies.json file can't turn off.

Oh, and verify these steps each time Firefox is updated.

How can I tell if I did it right?

If you want to verify that the policies file is working, open a new tab and type about:policies into the URL bar. You should see some settings similar to what's in the file.

Tell me More

I made a version of the file with commentary, so that you can see what each setting does. If you don't trust me (and why would you?) you can use this to make your own version. Firefox has some documentation about all this shit, and you can read that on their site.

But why though? Fair question. I most often get asked "why not use Librewolf or Arkenfox".

I don't use Librewolf because I don't want to rely on a massive third-party project which, as far as I can tell, doesn't do much that I don't already do, but requires several repositories and a large continuous integration deployment to do it. They don't limit themselves to privacy or security; they also disable shit I use. They'll disable Widevine and lecture you about how it's for your own good, but they'll also dump a ton of energy into maintaining a Windows port. I guess DRM is ok for the OS vendor, but not for you! On top of that, I have t-shirts older than the Librewolf project. Time will tell if they stick around. I hope they have fun, but I won't be using their software.

Arkenfox is basically a user.js file with a staggering amount of scaffolding around it. Before you can use a user.js file, you have to have a profile directory, which means launching Firefox, which means first-run telemetry. My way results in a first-run Firefox mostly configured the way I want, and I don't have to faff around with profile directories. I have more than one Firefox profile and my way means I don't have to do this over and over again. Arkenfox's documentation implores you in ALL CAPS to read their entire wiki, and I'm not going to do that, either. Again, I'm glad they're chasing their dreams, but I do not share them. There are a lot of also-ran projects which are nearly indistinguishable and not worth differentiating. What they have in common is they take themselves Very Seriously Indeed and you should not.

For the old instructions, which include support for Android stuff, you can read the old manual approach. Going forward, you can contribute to the maintenance of this file here.

This document was last updated on 20 September 2026 and was last tested with a clean install of Firefox 155.

Thanks to those who send corrections (this means you, prahou and leo)!

Strong recommendations

Once installed, you can open uBlock's preferences window, look at the 'Filter lists' tab, and add new filter lists. There's a section 'Cookie notices' which contains lists that try to block the stupid cookie consent banners.
Install the Cookie AutoDelete addon.
This deletes tracking data when you close a tab. You can allowlist websites where you want to stay logged in. Make sure to click on it and enable Auto-clean!
In about:config, find privacy.resistFingerprinting and set it to true. This makes it much harder for websites to infer your identity from browser idiocyncrasies. A lot of websites malfunction when this feature is activated. Be ready to revert this setting if something you use a lot falls over.

Optional extra steps

Add your own search engines: In about:config paste in "browser.urlbar.update2.engineAliasRefresh", make sure the "Boolean" radio button is selected, and click the plus sign on the far right. It should default to true. Now you can revisist the Search section and use the Add button you just earned. Use the form https://www.wiby.me/?q=%s with whatever search engine you want, using %s to stand in for the search term.
Disable Firefox's inbuilt password manager and use a better one; preferably, one not integrated into your browser. Disable "Autofill" both for addresses and credit cards.
In about:config, find dom.event.clipboardevents.enabled and dom.allow_cut_copy and set them to false.
This stops sites from tracking what you select, copy, or paste; it also stops sites from directly manipulating your clipboard. Turning these off may break sites like Google Docs or Office 365, so if you need those, skip this step.
In about:config, find media.autoplay.default and set it to 5, which blocks all autoplaying. Other values include 2 to prompt and 1 to autoplay without sound. Why isn't '5' the default? Because browser vendors are your enemies. In its defense, Netflix will break with this setting.
In about:config, paste the text ui.prefersReducedMotion, click the 'Number' option and the then the + button to the right. Set the value to 1 and click the checkbox to the right. This turns off all of the stupid tabs sliding around and so on.
In about:config, find network.trr.mode and set it to 3. Then find network.trr.uri and set it to https://dns.quad9.net/dns-query or https://dns.njal.la/dns-query. This forces all your DNS to the set endpoint using DoH. This effectively bypasses any local resolver you may have, such as a PiHole. In addition, many institutional networks block public DoH resolvers as a matter of policy. Be ready to revert network.trr.mode if DNS stops working in your browser.
In about:config, find media.peerconnection.enabled and set it to false.
This disables WebRTC, which works by establishing direct connections between people's browsers, potentially leaking information about your computer or network. However, WebRTC is used in some videoconferencing sites. If you're trying to video chat and it's not working you might need to turn this back on.
In about:config, find browser.cache.disk.enable and set it to false. Find browser.cache.memory.capacity and set it to 512000. Find media.memory_cache_max_size and set it to 256000. This significantly reduces the amount of disk I/O for caching, which is much easier on your SSD. These settings may cause performance problems in Firefox. Experiment to find the right balance between healthy caching and performance.
In about:config, find sidebar.revamp and set it to false.
This turns off the waste of screen space on the left-hand side. For now.
Go to DDG Privacy Essentials and click Add to Firefox
This thing blocks a lot of advertising spyware and gives you a report on how abusive a given website is. You don't have to care, though.
In about:config, find browser.compactMode.show and set it to true. This enables a menu option: to see it, click on the menu, select 'More tools', then 'Customize toolbar...' and you'll see a 'Density' button you didn't have before.
To get rid of the Firefox Sync spam in the main menu, open about:config, then find identity.fxaccounts.enabled and set it to false.

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