Transom

Transom is a native macOS browser-profile shell and web-link router. It groups windows from the same browser into a profile-oriented stack, adds a glass tab strip above the browser, and keeps grouped windows together when moved or resized.

Install

Requires macOS 13 or later on an Apple silicon Mac (M1 or newer). Current releases do not support Intel Macs.

1. Open the latest release and download Transom-VERSION-arm64.dmg from Assets.
2. Open the DMG and drag Transom into Applications.
3. Eject the disk image, then open Transom from Applications. It does not show a Dock icon. Right-click the browser overlay to open Settings… or quit Transom.
4. Grant access in System Settings → Privacy & Security → Accessibility. Reopen Transom if the browser overlay does not appear after granting access.
5. To route web links through the profile picker, open Settings… → Links, choose Make Transom Default Browser…, and confirm the system prompt.

Release downloads are Developer ID–signed and notarized by Apple.

To update, quit Transom from the overlay's right-click menu, download the latest DMG, and replace the existing app in Applications. Your settings remain in your user account.

Supported browsers

Transom discovers installed macOS versions of:

• Google Chrome
• Microsoft Edge
• Brave
• Vivaldi
• Opera
• Arc
• Chromium
• Helium
• Firefox
• Zen

Chromium-family profiles are read from Local State. Firefox and Zen profiles are read from profiles.ini. Transom resolves profiles from window titles and process arguments, retaining validated per-window assignments while windows remain open. Ambiguous multi-profile Chromium windows remain unidentified rather than being assigned the wrong profile.

Window overlay

• one independent glass container per running browser
• native AppKit segmented tabs with profile-colored indicators
• stable tab order while native window stacking changes
• exact-window switching through Accessibility APIs
• synchronized movement and resizing for grouped windows
• normal macOS window layering, spaces, and fullscreen support
• menu-bar accessory operation with no Dock icon

Web-link routing

Transom registers http and https handlers and can be selected as the default browser from Settings… → Links.

Unmatched links open a Spotlight-style profile picker with:

• browser and profile search
• keyboard navigation and Return/Escape handling
• browser icons and profile colors
• saved destinations for an entire site, a path and its subpaths, or an exact path, including custom paths

The Links section in Settings supports mappings using:

• host globs such as *.example.com
• host-scoped path prefixes and exact paths
• path regular expressions
• complete URL regular expressions

Regex rules take priority in list order. Site rules prefer the most specific matching path. Hold Option when opening a link to bypass automatic routing and choose a profile once.

Rules are stored at:

~/Library/Application Support/Transom/routing.json

Settings and themes

Open Settings… from the overlay’s native right-click menu. Settings include launch-at-login, window-manager compatibility, browser discovery, link routing, and overlay themes. Themes include Automatic, Light, Black, and all four Catppuccin flavors: Latte, Frappé, Macchiato, and Mocha. The URL opener follows the selected theme. Profile names and colors can be customized in Browsers. Turn off Show in picker beside a profile to hide it from the URL opener. Existing routing rules can still open that profile.

Build from source

mise run run

To run checks:

mise run check
mise run test

The built application is written to .build/Transom.app.

Linting and hooks

Install the pinned tools and local pre-commit hooks:

mise install
mise run hooks:install

The hooks check Swift formatting, shell scripts, GitHub workflows, property lists, Markdown, and spelling without modifying or staging files. Run all checks or apply formatting fixes explicitly:

mise run lint
mise run fmt:swift
mise run fmt:markdown
mise run lint:links

Link checks access the network and run separately in CI, not during commits. The generated changelog is excluded from formatting and spelling checks.