Documentation

Guides, FAQ, and reference for Umbra Browser.

Getting Started

Umbra is a privacy-focused browser that works just like any other Firefox-based browser, but with much stronger defaults.

  • Launch Umbra from your applications menu or run umbra from the terminal.
  • On first launch, you will see the Umbra onboarding page with an overview of your privacy tools.
  • uBlock Origin, AdNauseam, and TrackMeNot are pre-installed — check your extensions toolbar to configure them.
  • All privacy settings are pre-configured for maximum protection. You can adjust them in about:preferences#privacy.
  • To override specific preferences, create ~/.config/umbra/umbra/umbra.overrides.cfg.

Pre-installed Extensions

uBlock Origin

A wide-spectrum content blocker. Blocks ads, trackers, coin miners, popups, and malicious domains. Low memory footprint and highly configurable. Project page.

AdNauseam

An ad-blocker that fights surveillance by clicking on every ad it blocks, polluting advertiser data and protecting your profile. Built on uBlock Origin's engine. Project page.

TrackMeNot

A lightweight privacy tool that hides your actual search activity in a cloud of decoy queries, making it difficult for search engines to build an accurate profile of your interests. Project page.

These extensions are installed via Firefox's enterprise policy system and can be disabled or removed in about:addons.

Settings & Configuration

Umbra ships with a comprehensive configuration file (umbra.cfg) that sets all privacy, security, and behavior preferences.

  • Category breakdown: Privacy, Networking, Fingerprinting, Security, Region, Behavior, Extensions, Built-in Features, UI, Telemetry
  • Override file: Create ~/.config/umbra/umbra/umbra.overrides.cfg to change any default without editing the main config.
  • Reset to defaults: Delete your profile folder (~/.umbra/ on Linux) to get a clean start.

Most of the Umbra configuration is based on the excellent work by LibreWolf and arkenfox.

Building from Source

See the Downloads page for build instructions. The build process follows the same steps as LibreWolf.

FAQ

Is Umbra affiliated with LibreWolf?

No. Umbra is an independent fork of LibreWolf. We share the same goals of privacy and security, but we make different choices about defaults, extensions, and user experience.

Can I use Firefox extensions?

Yes. Umbra is fully compatible with Firefox WebExtensions. Install them from addons.mozilla.org.

How do I report a bug?

Open an issue on the GitHub repository.

Does Umbra have auto-updates?

Not built-in. We recommend using your system package manager (Linux) or downloading new releases manually. Auto-update functionality is intentionally disabled for privacy and security control.

Where can I find more documentation?

Since Umbra is based on LibreWolf, much of the LibreWolf documentation applies to Umbra as well. We recommend checking their FAQ for detailed questions about specific preferences.