cmux

cmux is a free and open source native macOS terminal built on Ghostty. It is described as a terminal for multitasking, organization, and programmability, with features such as vertical tabs, notification rings, split panes, and a CLI for automation. The interface is aimed at keeping terminals, agents, and related activity visible and controllable in one place.

Its vertical tabs include a sidebar that shows the git branch, working directory, ports, and notification text. Panes can be split horizontally or vertically within each tab, and notification rings light up when agents need attention. cmux also includes an in-app browser that can sit beside the terminal and is scriptable through an API. The browser automation documentation states that it can navigate, snapshot the DOM, click, type, evaluate JavaScript, and read console and network activity. Programmability extends through a CLI and socket API for tasks such as creating workspaces, opening split panes, sending input, reading screen contents, taking screenshots, and driving the browser.

The app supports extensive keyboard shortcuts, and its FAQ says terminal rendering uses Ghostty config while cmux-specific settings control the sidebar, tab bar, split panes, and behavior. It restores windows, workspaces, panes, working directories, and scrollback when relaunched, and that state survives a full computer restart. It also has an iOS companion in beta, with realtime terminal sync to iPhone and iPad, plus optional forwarding of terminal notifications. The FAQ says it works with any coding agent that runs in a terminal and names Claude Code, Codex, OpenCode, Gemini CLI, Kiro, Aider, Goose, Amp, Cline, and Cursor Agent among the examples. It can also open workspaces over SSH and attach to remote tmux sessions.

cmux runs on macOS only for now, as a native Swift and AppKit app. It is free to use, and the source code is available on GitHub. The page also says it is GPL-licensed.