A design experiment exploring what I think a browser should feel like.
Arjuna is a Firefox 149.0.2 fork built as a personal vision for browser UX — not a production browser. It was created to explore ideas around workspaces, dual sidebars, auto-hiding UI, and a distraction-free browsing experience. This is the final release.
Arjuna takes Firefox 149 and rethinks the interface:
- Workspaces — Built on top of Firefox containers. Each workspace is a container with its own tabs, tab groups, and state. Switch workspaces from the sidebar. New tabs auto-open in the active workspace.
- Dual Sidebars — Left sidebar for workspace switching. Right sidebar (inspired by Floorp) for bookmarks, history, downloads, synced tabs, extensions, and web panels with drag-and-drop reorder.
- Auto-hide Overlay UI — Toolbar and both sidebars collapse away when not in use. 6px trigger strips at window edges bring them back. The content area is always full-width.
- Vertical Tabs Only — Forced vertical tabs with no toggle. This is how it should be.
- Zero Clutter — Removed: Sponsored shortcuts, Firefox Labs, "More from Mozilla", Browser Layout settings, "Support Firefox" links, Recent Activity.
- No Sponsored Content — All sponsored content disabled at the branding level.
- Full Extension Compatibility — UA string reports as Firefox so AMO and all extensions work normally.
- Custom Branding — Arjuna logo, wordmark, About dialog, and application name throughout.
Arjuna is a design statement, not a maintained project. It exists to show what a browser could be if designed for people who live in their browser. There are known bugs, no automatic updates, and no security patches beyond what Firefox 149.0.2 shipped with.
Do not use this as your daily browser.
If you like these ideas, advocate for them in Firefox, Floorp, Zen, or whatever browser you use.
Download the AppImage from the Releases page.
chmod +x Arjuna-149.0.2-x86_64.AppImage
./Arjuna-149.0.2-x86_64.AppImageWorks on any x86_64 Linux distribution.
Arjuna is a set of patches applied to a clean Firefox 149.0.2 source tree.
- NixOS (or any Linux with the equivalent dependencies)
- ~16GB RAM, ~40GB disk space
- Patience (~77 minutes for a full build on 2 cores)
# 1. Get Firefox 149.0.2 source
wget https://archive.mozilla.org/pub/firefox/releases/149.0.2/source/firefox-149.0.2.source.tar.xz
tar xf firefox-149.0.2.source.tar.xz
mv firefox-149.0.2 sources/firefox
# 2. Apply the patch
cd sources/firefox
patch -p1 < ../../patches/arjuna-full.patch
# 3. Copy the build config
cp ../../mozconfig .
# 4. Enter the build environment and build
cd ../..
nix-shell shell.nix
cd sources/firefox
./mach build
# 5. Run
./mach runThe mozconfig hardcodes a NixOS libclang path. If you're on a different distro, update the --with-libclang-path line to point to your system's libclang.so directory.
| Patch | What it does |
|---|---|
01-branding.patch |
Logo, icons, app name, About dialog |
02-home-settings.patch |
Settings UI cleanup, sponsored content removal |
03-sidebar-secondary.patch |
Right sidebar with web panels, bookmarks, history |
04-toolbar-fixes.patch |
Auto-hide overlay system for all bars |
05-background-image.patch |
Custom background image |
arjuna-full.patch |
All of the above combined into one patch |
arjuna-nixos.patch |
NixOS-specific build fixes |
Arjuna is built on the work of others:
- Mozilla Firefox — The foundation. MPL 2.0.
- Floorp Browser — Right sidebar design inspiration. Code ported and rewritten.
- Built by Arjun with Claude Code.
MPL 2.0, same as Firefox.