Preview: These docs are available early so you can start using them now. Some pages may still be incomplete, outdated, or change as WebLibre develops.

Web Engine Hardening

WebLibre includes advanced browser engine preferences for people who want tighter control over privacy, network behavior, and attack-surface reduction.

These settings are for advanced users. The defaults already provide strong protection. If you’re unsure what a setting does, leave it at the default.

How to Open It

  1. Go to Settings > Privacy & Security.

  2. Tap Web Engine Hardening.

You can either apply a broad preset or open individual groups and change specific items.

What You See on This Screen

Complete Hardening

Applies WebLibre’s recommended hardening preferences across the available groups. This is the quickest way to turn on the non-optional recommendations.

Groups

Settings are split into named groups such as Safe Browsing, Telemetry, DNS, Secure Connections, Privacy, Resist Fingerprinting, WebRTC, Attack Surface Reduction, and PDFJS. Open a group if you want to review or change one area at a time.

Optional items

Some entries are marked Optional in the app. These are more aggressive changes that may cause compatibility problems, so they are not enabled by the one-tap hardening actions.

Reset all preferences

The menu on the hardening screen includes Reset all preferences, which clears your user-defined web engine hardening changes and returns those preferences to their defaults.

What These Groups Control

Here is the practical version of what the groups are for:

Safe Browsing

Controls protections against dangerous sites and downloads.

Telemetry

Reduces browser telemetry, studies, and other background data collection.

Block Implicit Outbound and DNS

Reduce background connections, prefetching, and DNS behaviors that can leak information.

Certificate Revocation and Secure Connections

Tighten certificate checks, HTTPS behavior, and secure connection rules.

Privacy and Resist Fingerprinting

Reduce cross-site leakage and make your browser harder to identify uniquely. For more on fingerprinting defenses, see Fingerprint Protection.

WebGL, WebRTC, API Restrictions, and Attack Surface Reduction

Limit or harden web features that can expose device details or increase the risk from malicious content.

Extension Security, Geolocation, Disk Avoidance, PDFJS, and Miscellaneous

Cover extension behavior, location services, what gets written to disk, built-in PDF viewer behavior, and a few extra privacy and security tweaks.

A Good Way to Use It

  1. Start with Complete Hardening if you want stronger defaults without reviewing every switch.

  2. If a website stops working, open the most relevant group and look for a recently enabled setting.

  3. Treat Optional items as troubleshooting or expert-only choices.

  4. If you are not sure what caused a problem, use Reset all preferences and re-enable only what you need.

Some hardening options can affect logins, video calls, PDFs, extensions, or how certain websites load. Stronger privacy often means a higher chance of site quirks.

Site Isolation

In WebLibre, this setting appears separately as Fission (Site Isolation) on the Privacy & Security screen.

Site Isolation runs each site in its own separate operating-system process. This adds protection if one site is compromised, because it helps isolate it from other sites you have open.

Expectation-setting: it uses more memory, and changing it requires an app restart.

Local Network Protection

These controls are also separate from the Web Engine Hardening screen. You can find them in the Network Protection section of Settings > Privacy & Security.

They help limit how websites interact with devices on your local network, such as printers, routers, cameras, or smart-home devices.

  • Local Network Access — Enables local network and device access blocking features

  • Block Local Network Requests — Blocks web page requests to local network addresses

  • Block Local Network Trackers — Blocks trackers from accessing local network resources

This can reduce network probing and device discovery from websites, but it may also interfere with sites that legitimately need to talk to local devices.

When You Probably Don’t Need This

If you already use WebLibre’s normal privacy features, many people do not need to manually change web engine hardening preferences. The screen is most useful when you want stricter behavior, want to review the browser’s low-level privacy choices, or are following a specific threat model.

If you just want stronger privacy with fewer decisions, start with the regular settings in Privacy & Security first, then come back here only if needed.