What specific Firefox settings and user.js customizations does LibreWolf apply compared to stock Firefox?

1. How LibreWolf enforces settings: overrides.cfg, user.js and pref() vs defaultPref()

LibreWolf documents that it uses configuration files read on every startup to apply Firefox preferences and distinguishes between defaultPref() (which only sets a default and can be changed by the user) and pref() (which writes a preference as if the user set it and thus enforces it) — the project leverages those mechanisms so some settings survive restarts and cannot be trivially re-enabled by profile-level changes ^[1].

2. Telemetry, network calls, and “search engine” defaults

Multiple community reports and LibreWolf’s own documentation indicate the build removes or disables a number of Mozilla telemetry and service calls that vanilla Firefox performs by default and that it ships without Google as a default search provider in some distributions, aiming to reduce outbound data collection and initial network calls that Firefox otherwise makes on first run ^{[3] [4]}. The precise list of telemetry preferences LibreWolf flips is documented in its settings pages but is not exhaustively enumerated in the reporting cited here ^{[1] [4]}.

3. Security hardening: strict pinning and download behavior

LibreWolf enables stricter public key pinning by default to block user-level man-in-the-middle interception by antivirus or similar software, and it documents how users must change security.cert_pinning.enforcement_level to reduce that strictness if they require such local MITM for legitimate reasons ^[2]. The project also changes download interaction defaults — asking for user interaction after each download — as an extra security measure layered on top of Firefox’s defaults ^[2].

4. Privacy features and fingerprinting tradeoffs

LibreWolf enables anti-fingerprinting measures such as letterboxing, which forces window resizing to fixed increments so the browser blends with larger cohorts rather than exposing exact inner-window sizes ^[1]. Community discussion notes that these and other aggressive privacy settings can break popular sites and that some users prefer lighter user.js approaches or the Tor Browser if their objective is the strongest anti-fingerprinting protection ^{[5] [3]}.

5. Bundled extensions and removed components (practical differences)

Users and forum posts report LibreWolf commonly ships with µBlock (or µBlock-origin) preinstalled and removes or disables certain Firefox built-in features such as form autofill to prevent automatic data collection; one community guide even documents needing to remove the formautofill extension from /opt/librewolf to change that behavior locally ^{[3] [4]}. Community threads summarize the practical difference as “Firefox with default settings changed and uBlock installed,” reflecting that LibreWolf’s experience is largely Firefox core plus curated privacy defaults ^[6].

6. Ecosystem context and alternative user.js approaches

LibreWolf is one of several projects that apply a user.js approach to harden Firefox; community-maintained user.js collections (arkenfox, pyllyukko, or minimal alternatives like vulpes) are often mentioned as alternatives and note that vanilla Firefox can be tuned to match many of LibreWolf’s changes via a custom user.js if users want different tradeoffs between site compatibility and privacy ^{[3] [5]}. The reporting also warns LibreWolf may feel “too harsh” to some users and that those seeking maximum anonymity should consider Tor Browser instead ^[5].

Limitations: the sources collectively describe the mechanisms LibreWolf uses and highlight prominent settings (PKP pinning, telemetry reduction, letterboxing, download prompts, bundled uBlock and removed autofill), but they do not publish a single, exhaustive list of every pref flipped in LibreWolf’s user.js/overrides in the excerpts cited here; readers seeking a line-by-line comparison should consult LibreWolf’s settings and overrides files directly on the project site or repository ^{[1] [2]}.