I’ve been using Windows at work for several years now, constantly switching between CMD and PowerShell for my daily development tasks. Although Windows Terminal has improved significantly, whenever I need to run multiple AI agents, check logs, and manage terminals simultaneously, I still end up opening a bunch of windows and Alt+Tabbing until I get dizzy. It wasn’t until I started working on this personal website project and discovered cmux on macOS that I truly understood what“a terminal designed for the AI era.”
What is cmux?
cmux is a native macOS terminal application built using Swift and AppKit (not Electron), based on the libghostty rendering engine from Ghostty. Its purpose is clear: it’s designed specifically for developers who run multiple AI code agents simultaneously.If you use tools like Claude Code, Codex, or Gemini CLI on a daily basis, cmux is the terminal built just for you. Plus, it’s completely free and open-source, licensed under GPL-3.0.
Seamless Window Switching
cmux uses a vertical tab system, with a sidebar that clearly lists all open workspaces. Each tab also displays information such as the Git branch, working directory, and listening ports. Switching between workspaces requires just a single shortcut key—the entire process takes place entirely within the terminal, without ever needing to take your fingers off the keyboard.
Thanks to GPU-accelerated rendering, scrolling and switching remain incredibly smooth even with multiple workspaces open—there’s absolutely no lag. This was the feature that really won me over the first time I used it.
Notification Ring: Automatic Alerts for Task Completion
This is the feature that surprised me the most, and it’s also the reason I initially wanted to share CMUX. When an AI agent in a workspace needs your input, a blue notification ring appears around the pane, and the corresponding tab in the sidebar flashes and displays a badge. Even better, it pushes desktop notifications directly through macOS’s native notification system.
No extra setup is required—it’s ready to use right out of the box. Cmd+Shift+U you can even jump straight to the latest unread notification. For us engineers who spend all day in the terminal, this is a godsend.
Split Panes: Do It All on One Screen
cmux supports both horizontal and vertical splitting within each workspace, allowing you to view multiple panels simultaneously. My standard setup while coding is: the dev server running on the left, Claude Code open in the top-right corner, and a terminal in the bottom-right for issuing commands at any time. You can keep track of everything on a single screen.
Built-in Browser: No More Switching Windows to View Screenshots
This feature really caught my eye. cmux includes a browser that can run side-by-side with the terminal, and it’s scriptable. Your AI agent can interact directly with the development server without having to manually switch to an external browser or configure port forwarding. It’s especially convenient when developing frontend code—you can see the results right next to you the moment you make a change.
Scriptable Control
cmux provides CLI tools and a Unix socket API, allowing you to control everything programmatically: create workspaces, split panes, send input, and control the built-in browser. This means you can write a script to launch your entire development environment with a single click, running different agents in each workspace with the layout automatically configured.
No-configuration design
cmux doesn’t require complex configuration files. There are no prefix keys to remember and no configuration files to maintain. If you’re already using Ghostty, cmux will automatically read your existing settings (fonts, themes, colors), making the transition completely seamless.
Supported AI Tools
cmux natively supports the most popular AI code agents:
Claude Code
Codex
Gemini CLI
OpenCode
Kiro, Aider, Goose, Amp, Cline
In fact, any tool that can be run in the terminal is supported
Other notable features
SSH support: You can set up remote workspaces, proxy browser traffic, drag-and-drop uploads, and agent notifications—all available remotely
Multi-agent orchestration: Native support for Claude Code teammates and oh-my-openagent
Lightweight and native: Built with Swift and AppKit for high system resource efficiency
Extensive keyboard shortcuts: Covers workspaces, splitting, browser functions, and more—and is fully customizable
Conclusion
cmux is more than just a terminal emulator; it’s a development workstation tailored for the AI era. As an engineer who has worked in a Windows environment for many years, I only realized after switching to cmux just how powerful a terminal can be. If you’re an engineer who interacts with AI agents and terminals on a daily basis, I highly recommend giving cmux a try—you’ll find you can’t go back.