Firefox user.js

A custom user.js script to configure Firefox user, privacy, and security settings. Supports Firefox 115+.

The goal is to make minimal changes to Firefox settings to enhance security and privacy without compromising on modern web features or making Firefox unstable or unsupported. Almost all of the settings configured by this script can be done through the Firefox settings and UI, so this script is a convenient time-saver.

This script can be used as a base for other user.js scripts.

Check the arkenfox/user.js repository for more information about user.js scripts.

Configured settings

A few user options are configured including setting Firefox as the default browser, hiding the bookmarks toolbar, and removing in-browser advertising.

Mozilla has increasingly relied on data collection to guide Firefox development and eroded user privacy in the process. For privacy, data collection is disabled from the following sources:

• Normandy can be used to stealthily modify Firefox settings without deploying a Firefox update.
• Studies have previously been used to remotely install add-ons without user permission.
• Activity Stream collects telemetry based on interactions with the new tab and homepage.
• Search and location bar suggestions send your search keywords to the default search engine.
• Firefox Health Report collects application metrics and submits them to a central server.
• Pocket collects numerous pieces of user data as per their Privacy Policy.

In addition, a few security settings are configured:

• Enhanced tracking protection blocks ad and social media trackers, cross-site cookies, cryptominers, and known fingerprinters.
• Fingerprint resistance prevents websites from easily identifying you on the web.
• HTTPS-only mode forces secure connections to all websites.
• Automatic form filling is disabled as this data can be phished.
• Links and DNS prefetching are disabled to prevent potential data leaks to third-parties and other security issues.

Installation

1. Go to about:profiles in the address bar
2. Open the Root Directory for the profile in use
3. Copy user.js into the root folder (so that the directory hierarchy is <root>/user.js)
4. Restart Firefox