about:config settings to harden the Firefox browser. Privacy and performance enhancements.
To change these settings type 'about:config' in the url bar.
Then search the setting you would like to change and modify the value. Some settings may break certain websites from functioning and
rendering normally. Some settings may also make firefox unstable.
I am not liable for any damages/loss of data.
Not all these changes are necessary and will be dependent upon your usage and hardware. Do some research on settings if you don't understand what they do. These settings are best combined with your standard privacy extensions
(HTTPS Everywhere No longer required: Enable HTTPS-Only Mode, NoScript/Request Policy, uBlock origin, agent spoofing, Privacy Badger etc), and all plugins set to "Ask To Activate".
https://github.com/arkenfox/user.js/wiki/4.1-Extensions
Some of these settings can actually make you more unique in some ways. There is a trade off. Evaluate your browsers fingerprint:
- https://panopticlick.eff.org
- https://browserleaks.com/
- https://amiunique.org/
- https://www.deviceinfo.me/
- https://abrahamjuliot.github.io/creepjs/
- https://wasm-feature-detect.surma.technology/
You can check current connections the your browser is making via about:networking
You can check current memory usage via about:memory
More information about most prefs, their values and effects can be found in mozilla docs here:
http://kb.mozillazine.org/Category:Security_and_privacy-related_preferences
http://kb.mozillazine.org/Category:Preferences
Also see: https://github.com/pyllyukko/user.js
dom.event.contextmenu.enabled = false
Don't allow websites to prevent use of right-click,
or otherwise messing with the context menu.
dom.event.clipboardevents.enabled = false
Don't allow websites to prevent copy and paste.
Disable notifications of copy, paste, or cut functions.
Stop webpage knowing which part of the page had been selected.
network.IDN_show_punycode = true
Show punycode. Help protect from character 'spoofing' eg:
xn--80ak6aa92e.com -> аррӏе.com
[IDN homograph attacks](https://www.xudongz.com/blog/2017/idn-phishing/)
plugins.enumerable_names = blank
Disable site reading installed plugins.
network.http.sendRefererHeader = 0
Tells website where you came from. Disabling may break some sites.
0 = Disable referrer headers.
1 = Send only on clicked links.
2 = (default) Send for links and image.
network.http.sendSecureXSiteReferrer = false
Disable referrer headers between https websites.
network.http.referer.spoofSource = true
Send fake referrer (if choose to send referrers).
privacy.trackingprotection.enabled = true
Mozilla’s built in tracking protection.
geo.enabled = false
geo.wifi.uri = blank
browser.search.geoip.url = blank
Disables geolocation and firefox logging geolocation requests.
browser.safebrowsing.enabled = false
browser.safebrowsing.phishing.enabled = false
browser.safebrowsing.malware.enabled = false
browser.safebrowsing.downloads.enabled = false
browser.safebrowsing.provider.google4.dataSharing.enabled = blank
browser.safebrowsing.provider.google4.updateURL = blank
browser.safebrowsing.provider.google4.reportURL = blank
browser.safebrowsing.provider.google4.reportPhishMistakeURL = blank
browser.safebrowsing.provider.google4.reportMalwareMistakeURL = blank
browser.safebrowsing.provider.google4.lists = blank
browser.safebrowsing.provider.google4.gethashURL = blank
browser.safebrowsing.provider.google4.dataSharingURL = blank
browser.safebrowsing.provider.google4.dataSharing.enabled = false
browser.safebrowsing.provider.google4.advisoryURL = blank
browser.safebrowsing.provider.google4.advisoryName = blank
browser.safebrowsing.provider.google.updateURL = blank
browser.safebrowsing.provider.google.reportURL = blank
browser.safebrowsing.provider.google.reportPhishMistakeURL = blank
browser.safebrowsing.provider.google.reportMalwareMistakeURL = blank
browser.safebrowsing.provider.google.pver = blank
browser.safebrowsing.provider.google.lists = blank
browser.safebrowsing.provider.google.gethashURL = blank
browser.safebrowsing.provider.google.advisoryURL = blank
browser.safebrowsing.downloads.remote.url = blank
Disable Google Safe Browsing and malware and phishing protection.
Stop sending links and downloading lists from google.
Security risk, but privacy improvement.
Note: this list may be incomplete as firefox updates, be sure to search for browser.safebrowsing.provider.google*
Also simply setting safebrowsing.*.enabled to false should make setting the URL's to blank redundant, but better to be safe.
If you see anything pointing google, probably best to nuke it.
browser.selfsupport.url = blank
browser.aboutHomeSnippets.updateUrL = blank
browser.startup.homepage_override.mstone = ignore
browser.startup.homepage_override.buildID = blank
startup.homepage_welcome_url = blank
startup.homepage_welcome_url.additional = blank
startup.homepage_override_url = blank
Can call home to every time firefox is started or home page is visited.
https://support.mozilla.org/en-US/kb/how-stop-firefox-making-automatic-connections
http://kb.mozillazine.org/Connections_established_on_startup_-_Firefox
toolkit.telemetry.cachedClientID = blank
browser.send_pings = false
Prevent website tracking clicks.
browser.send_pings.require_same_host = true
Only send pings if send and receiving host match (same website).
dom.battery.enabled = false
Disable website reading how much battery your mobile device or laptop has.
network.cookie.alwaysAcceptSessionCookies = false
Disables acceptance of session cookies.
network.cookie.cookieBehavior
Disable cookies.
0 = All cookies are allowed. (Default)
1 = Only cookies from the originating server are allowed. (block third party cookies)
2 = No cookies are allowed.
3 = Third-party cookies are allowed only if that site has stored cookies already from a previous visit
network.cookie.lifetimePolicy
cookies are deleted at the end of the session
0 = The cookie's lifetime is supplied by the server. (Default)
1 = The user is prompted for the cookie's lifetime.
2 = The cookie expires at the end of the session (when the browser closes).
3 = The cookie lasts for the number of days specified by network.cookie.lifetime.days.
network.dnsCacheEntries = 100
Number of cached DNS entries. Lower number = More requests but less data stored.
network.dnsCacheExpiration = 60
Time DNS entries are cached in seconds.
places.history.enabled = false
Disables recording of visited websites.
browser.formfill.enable = false
Disables saving of form data.
browser.cache.disk.enable = false
Disables caching on hardrive.
browser.cache.disk_cache_ssl = false
Disables caching for ssl connections.
browser.cache.memory.enable = false
Disables caching in memory.
browser.cache.offline.enable = false
Disables offline cache.
network.dns.disableIPv6 = true
If your OS or ISP does not support IPv6, there is no reason to have this preference set to false.
network.predictor.enabled = false
network.dns.disablePrefetch = true
network.prefetch-next = false
Link prefetching is when a webpage hints to the browser that certain pages are likely to be visited,
so the browser downloads them immediately so they can be displayed immediately when the user requests it.
network.http.speculative-parallel-limit = 0
Disable prefetch link on hover.
media.peerconnection.enabled = false
network.websocket.enabled = false
WebSockets is a technology that makes it possible to open an interactive communication
session between the user's browser and a server. (May leak IP when using proxy/VPN)
loop.enabled = false
Disable 3rd party closed-source Hello integration.
Note: only affects older versions of firefox as "Hello" has been discontinued as in favor of webrtc: https://support.mozilla.org/en-US/kb/hello-status
extensions.pocket.enabled = false
extensions.pocket.site = blank
extensions.pocket.oAuthConsumerKey = blank
extensions.pocket.api = blank
Disable 3rd party closed-source Pocket integration.
Note, this is browser.pocket.enabled for older versions of firefox
layout.frame_rate.precise = true
Increases animation speed. May mitigate choppy scrolling.
webgl.force-enabled = true
layers.acceleration.force-enabled = true
layers.offmainthreadcomposition.enabled = true
layers.offmainthreadcomposition.async-animations = true
layers.async-video.enabled = true
html5.offmainthread = true
Enable Hardware Acceleration and Off Main Thread Compositing (OMTC).
It's likely your browser is already set to use these features.
May introduce instability on some hardware.
browser.cache.memory.capacity = xx
Limit memory cache size. (xx = value in MB)
browser.sessionhistory.max_entries = xx
Limit maximum pages in session history. (how many URLs you can traverse using the Forward or Back button)
browser.sessionstore.max_tabs_undo = xx
Limit max closed tabs you can reopen.
browser.tabs.animate = false
browser.download.animateNotifications = false
Disable some animations.
config.trim_on_minimize = true
Reduce memory usage when minimized. (Windows only)
image.mem.max_decoded_image_kb = xx
How much info Firefox stores of uncompressed images.
Higher value = improve speed at the expense of increased memory usage.
javascript.options.mem.max == xx
Limit amount of memory javascript may consume.
-1 = Automatic
javascript.options.mem.high_water_mark == xx
Tell garbage collector to start running when javascript is using xx MB of memory.
Garbage collection releases memory back to the system.
This one is not for firefox, but for Flash if you have it installed. Font Enumeration allows a site to read which fonts you have installed which can be used to identify users.
Default Location:
Windows:
C:\Windows\SysWOW64\Macromed\Flash\mms.cfg
C:\Windows\system32\Macromed\Flash\mms.cfg
Linux:
/etc/adobe/mms.cfg
OSX:
~/Library/Application Support/Google/Chrome/Default/Pepper Data/Shockwave Flash/System/mms.cfg
Add this line to the mms.cfg file:
DisableDeviceFontEnumeration = 1
Better yet, simply uninstall flash. Flash is deprecated...Consider a VM
https://www.privacyguides.org/en/desktop-browsers/
Comparison: https://privacytests.org/
Users may want to consider LibreWolf as a better alternative to stock Firefox. LibreWolf comes with no telemetry and much better defaults out of the box:
Mulvad is another interesting Firefox fork to consider.
Users that prefer chrome: consider Brave or ungoogled chromium
https://github.com/ungoogled-software/ungoogled-chromium
** I do my best to keep this list up to date. Additions and corrections are greatly appreciated. Some keys may not be listed and must be added manually, or they are no longer relavent as firefox changes. **
This also breaks replit.com's console.