I got really tired of Firefox’s interface getting in my way, so I decided to completely rebuild it. This project is the result of way too many hours spent tweaking browser chrome and writing custom scripts to make Firefox work exactly how I want it to.
The Problem: Default UI Assumptions
Firefox’s default interface makes a lot of assumptions about how you browse the web. Giant address bar, huge tabs, tons of buttons I never use, menus full of options I don’t care about. For someone who spends most of their time in the browser, all that visual noise adds up.
I wanted something minimal, keyboard-driven, and optimized for actual productivity rather than looking pretty in screenshots.
The Three-Layer Solution
Configuration Layer (user.js): This is where I disable all the telemetry, advertising, and other stuff that Firefox tries to do by default. Also enables experimental features and tweaks performance settings. Basically makes Firefox behave more like a tool and less like a product trying to monetize my attention.
Styling Layer (userChrome.css): Custom CSS that completely redesigns Firefox’s interface. Smaller tabs, hidden buttons, repositioned elements, custom colors - everything you can’t change through normal settings gets modified here.
Scripting Layer (userChrome.js): JavaScript that runs in Firefox’s chrome context to add features that CSS alone can’t handle. This is where I implement keyboard shortcuts, automated behaviors, and UI modifications that require actual logic.
The Autoconfig Setup (Or: How to Hack Your Browser)
Getting userChrome.js to work requires installing the fx-autoconfig loader, which basically injects script execution into Firefox’s startup process. It’s a bit involved, but it opens up massive customization possibilities.
The loader sits in Firefox’s program directory and creates an execution environment for custom scripts. You have to be careful about security - this stuff runs with full browser privileges.
What I Actually Changed
Minimal Tab Bar: Redesigned tabs to take up way less vertical space and show more information density. Removed close buttons (I use keyboard shortcuts), customized the visual hierarchy, and added better visual feedback for tab states.
Aggressive UI Reduction: Hidden or moved most of the browser chrome to maximize content viewport. The address bar is smaller, bookmark bar is auto-hiding, and a bunch of buttons just aren’t there anymore.
Custom Context Menus: Stripped out all the useless options and reorganized the remaining ones to make sense. Added custom menu items that integrate with my external tools and workflows.
Keyboard-Everything: Implemented vim-style navigation keybindings throughout the interface. I can browse, manage tabs, and control pretty much everything without touching the mouse.
The Scripts That Make It Work
Session Management: Auto-saves and restores browsing sessions with custom logic. Selective tab loading to speed up startup, workspace context preservation, and intelligent handling of crashed sessions.
Privacy Automation: Scripts that automatically manage cookies, block trackers beyond what the built-in protections do, and resist fingerprinting attempts. This goes way beyond Firefox’s default privacy settings.
Performance Tuning: Automatic browser optimization based on usage patterns. Aggressive caching, resource allocation adjustments, and rendering pipeline tweaks that aren’t exposed in the normal settings.
Developer Integration: Enhanced developer tools with custom layouts and integrated debugging workflows. Makes web development way less painful by optimizing the tools I use most.
Why This Is Worth the Effort
After using this setup for a while, going back to default Firefox feels like using someone else’s computer with all the settings wrong. Everything is in the wrong place, there’s visual clutter everywhere, and simple tasks take more clicks than they should.
The performance improvements are real too. Startup is faster, memory usage is lower, and browsing feels more responsive. Part of that is removing unnecessary features, part is custom optimizations.
Link Handling: Custom protocols and automatic routing of different link types to appropriate applications. External links open in the right tools without manual intervention.
Search Engine Setup: Custom search definitions with keyword shortcuts and parameterized queries. I can search specific sites, documentation, or services with just a few keystrokes.
Download Management: Intelligent file organization, automatic naming, and integrated handling based on content types. Downloads go where they should without manual sorting.
The Security Trade-offs
Running custom JavaScript in the browser chrome isn’t something to do carelessly. I’ve implemented several safeguards:
- Restricted permissions on script directories
- Code review for any third-party scripts
- Regular security audits
- Minimal privilege principles
- Isolation of risky operations
But the reality is this setup requires more trust in your own code than most people are comfortable with. It’s definitely not for everyone.
Development Workflow
Live Reloading: Development setup that lets me test CSS and script changes without restarting Firefox. Makes the iteration cycle much faster when you’re tweaking things.
Comprehensive Docs: Everything is documented inline because future me always forgets why I made specific decisions. The docs explain not just what things do, but why they exist.
Version Control: All configs are versioned with proper backup and rollback capabilities. When you’re messing with core browser functionality, being able to undo changes is crucial.
This isn’t just a collection of tweaks - it’s a complete reimagining of how a browser interface should work for someone who lives in their browser. Every change exists because the default behavior was getting in my way.
The end result is a browser that feels like it was designed specifically for my workflow, because effectively, it was.
Repository: github.com/Thomashighbaugh/firefox