Browser

Leave all site settings permissions at ask to allow. Check browser anonymity/security with TorZillaPrint & Browser Leaks.

See the Arkenfox wiki.

Librewolf

Add Arkenfox’s user.js & Luke Smith’s overrides:: Make a new browser profile: about:profiles → Create a New Profile; Append the overrides to Arkenfox.; Place both .js files in the new profile (root directory).; Place updater.sh & prefsCleaner.sh in there.; Run both every once in a while.

Alternatively, there’s an AUR package.

Fennec F-Droid

Enable ETP:: Settings → Privacy and Security → Enhanced Tracking Protection → Enhanced Tracking Protection → ☑ Strict → ☐ Allow Fennec to automatically apply exceptions... → ☑ Tell websites not to share & sell data
Add Arkenfox’s user.js & Luke Smith’s overrides (requires root):: Append the overrides to the user.js file.; Place it at /data/data/org.mozilla.fennec_fdroid/files/mozilla/XXXXXXXX.default/; Set its owner & group to Fennec.

To enable installing extensions as normal, append this to the user.js:

user_pref("privacy.resistFingerprinting.block_mozAddonManager", "false")

Extensions

🛑 uBlock Origin – Blocks ads & scripts.
🍪 I still don’t care about cookies – Removes annoying cookie banners.
🌳 LocalCDN – Emulates CDNs locally.
🎯 LibRedirect – Redirects sites to privacy front-ends.

Set uBlock to hard or medium mode.

Enable AdGuard URL Tracking Protection & import Actually Legitimate URL Shortener Tool in uBlock. Both of these are pre-enabled on desktop.

Fix WebRTC leak with uBlock on mobile:: → ☑ Prevent WebRTC from leaking local IP addresses

Additionally these may be useful:

🖌️ Stylus – Changes any website’s colors.
🐒 Violentmonkey – Runs userscripts.

DNS over HTTPS

Enable DoH if not using Tor or I2P.

Librewolf:: Settings → Privacy and Security → DNS over HTTPS → ☑ Max Protection → Choose provider: Mullvad (No Filtering)
Fennec:: Settings → Privacy and Security → DNS over HTTPS → ☑ Max Protection → Choose provider: Custom → Provider: https://dns.mullvad.net/dns-query

Tor & I2P

Official Firefox config for I2P. The relevant about:config values are:

network.proxy.socks localhost
network.proxy.socks_port 4444 // 4447 for I2Pd, 9050 for Tor.
network.proxy.type 1 // 1 = enable, 5 = use system proxy

! Remember to set this:

network.dns.disabled true

Otherwise if the proxy isn’t running or connected .onion & .i2p addresses will be sent to your VPN or ISP.