cmux
A native macOS terminal built for multitasking with coding agents, featuring vertical tabs, split panes, an embedded browser, and a socket API.
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Product Overview
What is cmux?
cmux is a native macOS terminal application developed by Manaflow, built on top of libghostty — the rendering engine behind Ghostty — rather than being a fork of it. It is purpose-built for developers running multiple AI coding agents simultaneously, such as Claude Code, Codex, Gemini CLI, Aider, and others. Written in Swift and AppKit, cmux is lightweight, GPU-accelerated, and requires no config files or prefix keys. It extends beyond a conventional terminal by offering a built-in browser, notification rings for agent attention, and a fully scriptable CLI and socket API. cmux is free and open source.
Key Features
Vertical Tab Sidebar
Each tab in the sidebar displays the current git branch, working directory, open ports, and notification text, giving developers a clear overview of all active sessions at a glance.
Agent Notification Rings
Visual notification rings alert developers when a coding agent is waiting for input, preventing idle agents from going unnoticed during multitasking.
Split Panes
Supports both horizontal and vertical splits within each tab, enabling side-by-side terminal sessions or a terminal paired with the built-in browser.
In-App Browser
An embedded browser can be displayed alongside the terminal with a scriptable API, eliminating the need to switch between apps when referencing documentation or previewing outputs.
Scriptable CLI & Socket API
Full automation support via a CLI and socket API — create workspaces, manage tabs, split panes, send keystrokes, and open URLs programmatically.
Lightweight Native Performance
Built with Swift and AppKit with GPU acceleration via libghostty, cmux avoids Electron overhead for a fast, resource-efficient experience.
Use Cases
- Multi-Agent Development : Developers running multiple AI coding agents (e.g., Claude Code, Codex, Aider) in parallel can monitor all sessions from a single window with clear visual cues for agent status.
- Terminal Automation & Scripting : DevOps engineers and power users can automate complex workflows by scripting workspace creation, pane management, and keystroke injection via the socket API.
- Documentation-Alongside-Coding : Developers can split the terminal and the built-in browser side by side, referencing API docs or web previews without leaving the coding environment.
- Multi-Project Workspace Management : Teams or individual developers managing several projects simultaneously benefit from tab-level context (branch, directory, ports) to stay oriented across all workspaces.
FAQs
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