2018-11-14 Firefox Setup

New laptop at the office... These settings reflect my own compromise between usability, security and privacy. I’ll try to comment my choices, though.


uMatrix requires some interaction every now and then. You’ll get the hang of it, eventually. 🙂 Essentially: when a site breaks, open it up, think about the red stuff you want to enable and do that by clicking into the top half of the squares to allow stuff; click into the bottom half to disallow stuff. Reload every now and then until you’re happy. If you want to keep these settings, click on the lock. If you want to revert it all, click on the two arrows going in a circle.

2020-02-16: I used to list “HTTPS by default” as well. Not sure I still need it, though. It’s also pretty annoying because I still visit sites that are HTTP only.


media.autoplay.default = 1

(1 means always block, 2 means you want to be prompted for every site that tries to autoplay...)

If all the text seems too small to read comfortably, use the following instead of zooming every page to 150%:

layout.css.devPixelsPerPx = 1.5

Sadly I don’t remember what else to change right now!


Remember that you can import your bookmarks from an old profile via the library / bookmark manager.


The rest of this page is about your preferences. Depending on your version of Firefox or PureBrowser or whatever you are using, the exact labels might differ.


This is from the preferences in search (the looking glass icon).

Privacy & Security

This is from the preferences in privacy/security (the padlock icon).

Choose custom.

Further down:



@sohkamyung says:

  • “If PureBrowser supports it, try Multi-account Containers too. It silos cookies and maybe other stuff too.”
  • “For cookie management, you can try the Cookie Autodelete extension. You can use it to whitelist some sites, and it autodeletes cookies from other sites once you leave them and close the tab view.”
  • “Maybe the Firefox Temporary Containers extension might be of use.”

@fitheach says:

  • “I also use the randomised User Agent feature of uMatrix.”

@BartG95 notes:

  • “NoScript is missing?” (When I tried it a long time ago, that really did break a lot of the web. Perhaps I’m better prepared for the experience, now?)

@chozron says:

  • “I also recently turned on first party isolation in Firefox.”

@silkevicious recommends:

@maiki mentions Customizing Firefox using auto config:

The AutoConfig file can be managed centrally. To do so, the location of a secondary AutoConfig file in the primary AutoConfig file:

pref(”autoadmin.global_config_url”, “http://yourdomain.com/autoconfigfile.js”);

@fitheach has a customised version of this and says: “Some settings can be quite restrictive and I’ve disabled them. Best thing is to install as is, if a site doesn’t work disable some likely settings.”

@RedLore recommends an article on Restore Privacy which gives you a list of all the about:config changes to make to increase privacy on Firefox.

@steven also recommends https://privacytools.io and says it “is a great reference for privacy in general, and it recommends add-ons and about:config tweaks. Although it’s a website, it’s also an open source project, so you can look at the bug and feature requests to see the rationale behind their recommendations.”

– Alex Schroeder 2019-03-31 08:38 UTC

A year later...

layout.css.devPixelsPerPx = 1.5


– Alex Schroeder 2020-01-02 14:01 UTC

A few months later... Something is wrong with my uMatrix, but what? The icon says 2 items, but when I open the extension’s tab, I always get the “all” and “” stuff, never the actual domain names. I use Firefox 68.6.0esr (64-bit) – and uMatrix 1.3.16.

@ashwinvis tells me they gave up on uMatrix and just use Origins advanced mode instead. This sounds like a good idea and I will try it.


  • 3rd-party scripts
  • 3rd-party frames

Let’s see how it goes!

– Alex Schroeder 2020-03-19 10:57 UTC

Twitter and YouTube Alternatives using Redirector

I’ve started using Redirector with the following rules (you can import and export them from the add-on’s preferences):

    "createdBy": "Redirector v3.5.2",
    "createdAt": "2020-06-10T11:56:28.300Z",
    "redirects": [
            "description": "Twitter to Nitter",
            "exampleUrl": "https://twitter.com/neiltyson/",
            "exampleResult": "https://nitter.net/neiltyson/",
            "error": null,
            "includePattern": "https://(.*\\.)?twitter.com/(.*)",
            "excludePattern": "",
            "patternDesc": "all twitter domains go to nitter",
            "redirectUrl": "https://nitter.net/$2",
            "patternType": "R",
            "processMatches": "noProcessing",
            "disabled": false,
            "appliesTo": [

– Alex Schroeder 2020-06-10 11:57 UTC

@lemming linked me to Disable clipboard events override in Firefox:

dom.event.clipboardevents.enabled → false

Now websites can’t override any clipboard events! That is,they can not prevent you from pasting passwords, for example.

– Alex Schroeder 2020-06-26 11:29 UTC

@andreas links to the following: “Mozilla works with advertising partners to place sponsored tiles on the Firefox home page (or New Tab) that would be useful to Firefox users. Mozilla is paid when users click on sponsored tiles.” – Sponsored Top Sites

browser.newtabpage.activity-stream.showSponsoredTopSites → false

– 2020-11-21 20:14 UTC

I recently noticed that my cache size in “~/.cache/mozilla” was 1.1G. @penguin42 recommended looking at about:config and so I did. Here’s what you need to do:

browser.cache.disk.capacity → reset to default (256000)
browser.cache.disk.smart_size_enabled → false

If you don’t disable smart sizing, the cache capacity you set gets overwritten. What would be a good size? I don’t know.

– Alex 2021-01-01 12:49 UTC

I hate backspace going back in history.

browser.backspace_action → 2

– Alex 2021-03-23 10:10 UTC

Javascript inside PDF files? Enabled by default in Firefox 88.

pdfjs.enableScripting → false

– Alex 2021-05-30 11:16 UTC

Every few months, more problems.

datareporting.policy.dataSubmissionEnabled → false
toolkit.telemetry.archive.enabled → false
toolkit.telemetry.server → <clear value>
toolkit.telemetry.unified → false

The following should be the default already:

datareporting.healthreport.uploadEnabled → false 
toolkit.telemetry.enabled → false

Basically I search for telemetry*enabled and switch it all too false, because I don’t understand why we need a bewildering plethora of options when almost all people will be either “I don’t care” or “fuck this shit”. This is false choice designed to confuse the unwary, if you ask me.

– Alex 2021-07-14 12:25 UTC

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