about:config Settings Worth Changing (and What Not to Touch)

about:config is Firefox's advanced settings panel, containing hundreds of internal preferences. Most users never modify it. However, tweaking a few settings can significantly enhance privacy and performance. To access about:config, type the phrase into your browser's address bar, accept the warning, and then search for the desired settings.

Each setting has a name, type, status, and value. Boolean settings toggle with a double-click, while integer and string settings allow editing upon a double-click.

Some settings worth considering are:

1. DNS over HTTPS (Forced Mode): network.trr.mode = 3 forces all DNS queries through your DoH resolver. Use this only if your resolver is reliable. You can set your preferred resolver using network.trr.uri = https://<resolver>/dns-query. Alternatives include Quad9, NextDNS, or AdGuard.

2. Encrypted Client Hello (ECH): network.dns.echconfig.enabled = true and network.dns.http3_echconfig.enabled = true encrypt the SNI in TLS handshakes. This protects your visited hostnames from passive observers on Cloudflare-hosted sites.

3. WebRTC Local IP Leaks prevention: media.peerconnection.ice.no_host = true prevents WebRTC from revealing your local network IP addresses while still allowing video calls via relay.

4. Fingerprinting resistance: privacy.fingerprintingProtection = true, privacy.resistFingerprinting = true (Firefox 117+) standardize browser properties, making your browser less identifiable. However, privacy.resistFingerprinting can break some sites, so privacy.fingerprintingProtection may be a better option.

5. Sanitize History on Shutdown: privacy.sanitize.sanitizeOnShutdown = true and privacy.clearOnShutdown.cookies = true privacy.clearOnShutdown.history = true clear cookies and history when Firefox closes. This is useful for shared computers or high-privacy profiles.

Some settings NOT worth changing include javascript.enabled = false, network.http.sendRefererHeader = 0, and network.http.pipelining = true. These changes can break essential functionality or provide minimal privacy benefits. Instead, consider using a user.js file or the Arkenfox user.js project to apply your preferred settings automatically on Firefox startup. Always back up your current settings before making changes and be cautious when experimenting with about:config.