cmux Review (2026): The AI-Agent-Aware Terminal for macOS
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An in-depth review of cmux, a free GPU-accelerated macOS terminal built on Ghostty's engine and designed for running multiple AI coding agents.
Running multiple AI coding agents in parallel—such as Claude Code instances, Codex, or Gemini CLI sessions—typically requires juggling multiple terminal tabs or managing complex tmux configurations. Without visual feedback, it is difficult to identify which agent is waiting for input, which has completed its run, or which has run into an error.
cmux is a native macOS terminal designed to address this problem by treating AI agent orchestration as a first-class feature. Built on the core rendering engine of the Ghostty terminal, it combines speed with agent-aware visual notifications, a built-in browser for documentation reference, and a scriptable API.
What Is cmux?
cmux is a free, open-source terminal application for macOS built on the Ghostty rendering engine (specifically the libghostty library). Launched in February 2026, the project has grown rapidly, accumulating over 22,000 GitHub stars by mid-2026.
Rather than acting as a general-purpose terminal emulator, cmux is tailored for multi-agent workflows. It provides vertical tabs, status rings to track agent progress, and an embedded browser to consult documentation side-by-side with active sessions.
Key Features
| Feature | Details |
|---|---|
| Ghostty Engine | GPU-accelerated rendering via libghostty for high-performance text output. |
| Vertical Tabs | A sidebar displaying active terminal sessions with dedicated status indicators. |
| Agent Notifications | Color-coded visual badges that update based on agent activity and requirements. |
| Built-in Browser | An in-app reference panel to check documentation, pull requests, or API links. |
| Scriptable CLI | A socket API enabling programmatic control and automation of terminal panes. |
| Ghostty Config Compatibility | Drop-in compatibility with existing Ghostty configuration files. |
| Themes | Integrated support for popular themes (like Catppuccin) with animated gradients. |
Agent Notifications
The primary differentiator for cmux is its visual indicator system. When running parallel tasks, cmux updates the status ring of each tab:
- Green: The agent has successfully completed its task.
- Yellow: The agent is paused and waiting for user input.
- Red: The process has encountered an error.
These indicators reduce the need to manually cycle through active tabs to check if an agent requires attention.
Built-in Browser
An embedded web browser panel can be opened in a split pane next to the terminal. This allows developers to check API documentation, view GitHub issues, or read specifications without switching applications. It acts as a lightweight reference panel rather than a full-featured general web browser.
Installation
cmux is distributed through Homebrew. You can install the cask from its official repository:
brew tap manaflow-ai/cmux
brew install --cask cmux
To update an existing installation:
brew upgrade --cask cmux
To add shell integration for Zsh, include the following in your shell configuration:
eval "$(cmux shell zsh)"
Users with existing Ghostty configurations will find that cmux automatically imports and respects those settings.
cmux vs tmux
| Feature | cmux | tmux |
|---|---|---|
| Platform | macOS only | Cross-platform (Linux, macOS, BSD) |
| Rendering | GPU-accelerated (libghostty) | Dependent on the host terminal emulator |
| Agent Notifications | Built-in visual indicators (colors/badges) | None (requires custom scripting) |
| Browser | Built-in reference panel | None |
| Scriptable | CLI and socket API | Comprehensive built-in scripting language |
| Session Persistence | No live restore on relaunch | Full session persistence |
| SSH Persistence | Yes (session detach/reattach) | Yes |
| User Interface | Native macOS GUI with custom themes | Text-based user interface (TUI) |
| Learning Curve | Low | Medium to high |
cmux is optimized for local GUI-driven development on macOS, leveraging visual states to streamline parallel agent tasks. Conversely, tmux is cross-platform, text-only, and remains the standard for terminal multiplexing, remote server sessions, and persistent environments.
Pros and Cons
| Pros | Cons |
|---|---|
| High-performance GPU rendering via Ghostty | macOS exclusive (no Linux or Windows support) |
| Real-time visual indicators for agent status | Lacks session restoration on application relaunch |
| Built-in browser pane for quick documentation lookup | Young project with occasional stability or sandbox issues |
| Scriptable CLI with a local socket API | Smaller ecosystem and user community compared to tmux |
| Compatible with existing Ghostty configs | |
| Free and open-source (GPL-3.0-or-later) |
Target Audience
cmux is a strong fit for:
- macOS developers who regularly execute command-line AI agents such as Claude Code, Codex, or Gemini CLI.
- Users looking to run three or more AI agents concurrently without losing track of their execution states.
- Developers already using or migrating from the Ghostty terminal who want agent-specific visual enhancements.
cmux is a weaker fit for:
- Developers operating on Linux or Windows environments.
- Workflows that require reliable session persistence across system restarts.
- Traditional terminal users who do not run automated, agent-based CLI tools.
Verdict
cmux provides a dedicated desktop environment for local multi-agent AI development on macOS. By wrapping Ghostty's high-speed rendering engine with agent-aware status rings, a companion reference browser, and a control socket, it addresses the coordination challenges of running parallel agent tasks.
While it lacks the cross-platform availability and session persistence of traditional multiplexers like tmux, it offers a tailored desktop-native alternative for macOS-based developers working closely with command-line AI assistants.