BrowserMux

A modern browser selector for Windows 11. Choose which browser, or which profile, opens each link.

Download · Report a bug

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Why

Every link you click on Windows goes through a single "default browser". That's fine until you juggle a work profile, a personal profile, a dev Chromium, and the odd Firefox window. BrowserMux replaces the default with a tiny picker that pops up under your cursor, lets you choose, and gets out of the way.

Similar to Hurl and BrowserSelect, but with browser profile support. Built from scratch in 2026 with WinUI 3, Fluent Design, and Mica.

Features

• Pops up under the cursor: DPI-aware, multi-monitor, disappears on lost focus.
• Detects Chromium profiles automatically (Chrome, Edge, Brave, Vivaldi, Opera): each profile is a separate card.
• Routing rules: send github.com to Firefox Work, *.google.com to Chrome Personal. Domain / glob / regex.
• Routing rules Quick add with Shift+Click.
• Incognito / private mode with Alt+Click.
• Keyboard-first: 1-9 to pick, Tab to navigate, C to copy URL, Esc to cancel.
• Custom browsers: add portable or unregistered executables.
• Drag-and-drop reorder in Settings.
• System tray icon with quick access to the launcher and settings.
• Auto-update from GitHub releases.
• Fluent Design: Mica backdrop, light/dark/system theme.

Privacy

Zero telemetry. BrowserMux never phones home, never collects usage data, and never sends URLs anywhere. The only network call it ever makes is to api.github.com to check for a new release — and you can disable that in Settings → Updates.

All preferences and rules live in %LOCALAPPDATA%\BrowserMux\ as plain JSON.

Install

1. Download the latest BrowserMux-Setup-x.y.z.exe from the Releases page.
2. Run the installer. By default it installs per-user (writes to HKCU). You can elevate to install machine-wide (HKLM).
3. Open Settings → Apps → Default apps and set BrowserMux as the default for http and https. BrowserMux can take you there directly from its About tab.

A portable zip is also published if you'd rather not install. Note: the portable build can't be set as the system default browser without the registry entries the installer adds.

Requirements: Windows 10 (1809+) or Windows 11, .NET 9 Desktop Runtime (x64). The installer will prompt if missing.

Footprint: ~10 MB installer, ~ 50MB on RAM. The URL handler is a C# AOT native binary (<2 MB) with sub-50 ms cold start.

Why does it need to be the default browser?

Windows only forwards http/https clicks to whichever app is registered as the default browser. For BrowserMux to intercept a link, Windows has to send it to BrowserMux first. The tiny BrowserMux.Handler exe receives the URL, forwards it over a named pipe to the main app (which shows the picker), and then the real browser you chose opens the link. BrowserMux itself never renders web content — it's a router, not a browser.

SmartScreen warning

Current releases are not code-signed, so Windows SmartScreen will show a "Windows protected your PC" dialog on first run. Click More info → Run anyway. An EV code-signing certificate is on the roadmap and will be applied to future releases — feedback welcome in the issues.

Usage

Picker

Key	Action
1 – 9	Open the Nth browser
Tab / Shift+Tab	Navigate between cards
Enter	Open the selected card
Alt+click	Open in private/incognito mode
Shift+click	Create a routing rule for this domain
C	Copy URL to clipboard
Esc	Close without opening

Rules

Open Settings → Rules to configure automatic routing. Each rule matches a URL against a pattern and sends it to a specific browser (or forces the picker to show, useful for exceptions).

Launcher

Bind a global hotkey in Settings → General → Launcher hotkey to open the picker without a URL. Useful as a quick launcher.

Build from source

Prerequisites

• Windows 11
• Visual Studio 2026 with Windows App SDK workload
• .NET 9 SDK
• Inno Setup 6 (only to build the installer)

Build & run

pwsh build.ps1 -Run

build.ps1 goes through MSBuild (not dotnet build) so referenced projects rebuild correctly. Use -Clean for a full clean rebuild, -Url "https://example.com" to launch with a specific URL.

Build the installer

pwsh build-installer.ps1

Outputs to dist/.

Architecture

Three C# projects, .NET 9, WinUI 3 for UI and C# AOT for the URL handler (sub-50ms cold start).

BrowserMux.Handler/   AOT exe registered as default browser. Forwards URL via named pipe.
BrowserMux.App/       Main WinUI 3 app. Picker, Settings, tray icon, MVVM.
BrowserMux.Core/      Models + pure services (detection, rules, preferences).
Installer/setup.iss   Inno Setup 6 script (HKCU/HKLM registration).

See CLAUDE.md for the full technical breakdown.

Contributing

See CONTRIBUTING.md for dev setup, build tips, and PR guidelines.

Built with Claude Code

I'll be upfront: most of BrowserMux was written with Claude Code driving the keyboard. I'm a solo dev who wanted a tool that didn't exist (maintained and supporting browser profiles), and it's thanks to AI-assisted coding that a project of this kind can come together in just a couple of hours of work.

That doesn't mean it's sloppy. The CLAUDE.md, docs/, and .claude/skills/ files you'll see in the repo are the operating manual I've built up over the project — architecture rules, Win10 compatibility gotchas, build quirks, doc conventions. They're checked in on purpose, not leftovers. Every change goes through my review, the app runs on my own machine every day, and I own every bug.

If "vibe-coded" is a dealbreaker for you, fair enough — the source is right there, read it and judge. If you find something broken or ugly, open an issue.

License

MIT © 2026 BrowserMux contributors.

Credits

• Icon extraction via Shell32.
• Built with WinUI 3 and CommunityToolkit.Mvvm.