arkenfox user.js
A settings file that hardens Firefox for privacy and security: about 150 changes applied every time Firefox starts, plus scripts to keep your own overrides when it updates.
What you can do with it
- A locked-down second Firefox profile that wipes cookies every time you close it
- Strict tracking protection and lighter fingerprinting defaults in one go
- Optional resist-fingerprinting mode that hides your real time zone, CPU and graphics card
Worth knowingIt's made for people who read the docs: some sites will break, you'll be logged out every time you close Firefox unless you add exceptions, and the optional RFP mode shifts website clocks to GMT.
The full tutorial
01See what you're about to changeFREE02Make a separate Firefox profile with its own shortcutMEMBERS03Download arkenfox and write your overridesMEMBERS04Build your user.js and check it workedMEMBERS05Live with it: logins, broken sites and updatesMEMBERS06Optional: resist fingerprinting, and what it breaksMEMBERS
Harden Firefox until websites think you're in Iceland, without touching your normal browser · ~25 min · tested 2026-10-09
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