mmux vs cmux

What is cmux?

cmux describes itself as "a Ghostty-based macOS terminal with vertical tabs and notifications for AI coding agents" [1]. It is a native app written in Swift and AppKit that uses libghostty for rendering and reads your existing Ghostty config for themes, fonts and keybindings [1]. It is not a fork of Ghostty [1].

Its main additions over a plain terminal are a sidebar of vertical tabs (showing git branch, linked PR, working directory, listening ports and the latest notification), a notification system that picks up OSC 9/99/777 escapes or the cmux notify CLI, an in-app browser that agents can drive, and a CLI plus socket API to create workspaces, split panes and send keystrokes [1]. The project calls itself "a primitive, not a solution" [1], and for that reason has said it will not add built-in git worktree support [5].

cmux is made by Manaflow, a Y Combinator Summer 2024 company in San Francisco [6]. The app is free and GPL-3.0-or-later, while its server components are under BUSL-1.1 [7]. Paid Pro, Max, Team and Enterprise plans add cloud VMs, the iOS app and team features [4]. The repository also contains a Rust TUI called cmux-tui, but it is not part of the release downloads we checked [3], so this page compares the macOS app.

Where cmux is better

• Several things on screen at once. cmux has tabs and horizontal and vertical splits, so you can watch two agents and a dev server side by side [1]. mmux shows one program in its main pane at a time; you switch between them from the sidebar.
• A browser next to the terminal. cmux can split a browser pane beside a terminal, and agents can snapshot the page, click, fill forms and read console output through the same API [1]. mmux has nothing comparable.
• A native Mac app. GPU rendering through libghostty, your Ghostty config, macOS keyboard shortcuts, Sparkle auto-updates and a DMG install [1]. mmux is a TUI, so how it looks and feels depends on the terminal you run it in.
• Notification handling. Besides desktop notifications, cmux keeps a notification panel, marks panes with a ring and has a shortcut to jump to the latest unread [1]. mmux colors sidebar rows and sends a desktop notification, but keeps no history of them.
• More agents resume. cmux lists resume support for 13 agents, among them Claude Code, Codex, OpenCode, Gemini, Amp and Copilot [1]. mmux resumes Claude, Codex, Pi and Grok conversations.
• Phone and cloud. cmux has an iOS app (beta) that pairs with your Mac, and paid cloud VMs to run agents in isolated sandboxes [1][4]. mmux has neither; on a phone you SSH in and mmux switches to a single-column layout.

Where mmux is better

• Linux and any terminal. mmux is one binary for macOS and Linux that runs in iTerm2, Ghostty, kitty, WezTerm, a plain SSH session or cmux itself. cmux is macOS only [1].
• Persistent by default. Every mmux runs inside an invisible tmux session, so closing the window or losing an SSH connection detaches instead of killing your agents. In cmux, quitting restores the layout and resumes supported agents, but live processes only survive if you opt in with cmux local-tmux [1][2].
• Runs where the code is. On a remote server, mmux runs on that server and you attach with any SSH client, from any computer. Desktop notifications still reach your local terminal through OSC escapes.
• Dev processes as first-class rows. Dev servers and scripts are declared in mmux.yaml, started and stopped from the sidebar, can run a stop: command on quit, and only one checkout of a repository runs a given process at a time so ports do not clash.
• Git panel and worktrees built in. Stage, commit (with an AI-suggested message), switch branches and push from the right-hand panel. Press w and a worktree opens as its own project box with its own agents and processes; M merges it back. cmux leaves worktrees to your own scripts on purpose [5].
• Projects grouped by directory. One mmux per directory, and a workspace manifest can bundle several repositories into one sidebar.

When to use which

Using cmux and mmux together

cmux is a terminal and mmux is a terminal program, so you can run mmux inside a cmux tab. You keep cmux's rendering, splits and browser pane, and mmux keeps the agents alive when you quit cmux.

1. Install mmux (it needs tmux on your PATH).
2. Open a cmux workspace in your project and run mmux. Reattach later with mmux attach.
3. mmux's default osc9 notifications are an escape that cmux listens for [1], so an agent that needs you should still raise cmux's notification cues. We have not tested this combination.

cd ~/some/project
mmux init
mmux