Minimal, customizable Firefox/LibreWolf setup built with userChrome.css, bringing a Zen Browser sidebar workflow to stock Firefox or LibreWolf — no fork, no build.
Default
Zen Mode
🧩 Enhanced Sidebery Integration - Urlbar in the sidebar, expands on focus; optional sidebery.css for native-style larger tab icons
🧘 Zen Mode - Toggle the sidebar to hide the UI and maximize focus
✨ Minimal Chrome - Only the essentials, coherent with a keyboard-driven UX
🤝 Built to Customize - Clean code and detailed docs to support customization and contribution
🎨 Theme Support - System themes (light/dark) and user-created Firefox themes supported
Fennec is for people who want the Zen-style sidebar workflow while staying on stock Firefox or LibreWolf.
- No browser fork — just CSS
- Update-safe customizations — your tweaks survive Fennec updates
- Works on Firefox and LibreWolf
Please see security considerations before installing
Install Sideberry, then run:
macOS / Linux:
curl -fsSL https://raw.githubusercontent.com/tompassarelli/fennec/main/install.sh | bashWindows (PowerShell):
irm https://raw.githubusercontent.com/tompassarelli/fennec/main/install.ps1 | iexLibreWolf: add --librewolf to either command.
See the full installation guide for manual install, flags, and details.
- Extensions are privileged software — install only ones you trust
- Zen Mode can hide browser security indicators; verify pages before browsing with the UI hidden
- Review install scripts before piping them into your shell
- Fennec is a UI customization, not a security tool — use it with normal caution
Actively maintained with recent releases and ongoing improvements. If something isn't working, check open issues or file a new one.
Fennec draws inspiration from:
- Zen Browser — sidebar design
- parfait — findbar and accessibility