cmux vs Roost

Where they differ

• One host versus a fleet. cmux is an application that runs on your Mac and owns the terminals on that Mac. Roost is a coordinator plus any number of workers: every macOS and Linux machine you connect on one coordinator, grouped in one sidebar with per-machine CPU, memory, disk, and network tiles. The coordinator machine is itself a worker, so a one-box install is the degenerate case rather than a different product.

• What counts as the client. cmux’s client is the Mac it is installed on; reaching it from elsewhere means the TestFlight iOS companion or its beta SSH and remote-tmux paths, which are ways for a local app to reach a remote shell. Roost inverts the direction: the coordinator holds the sessions, any browser is a full client on a laptop, an iPhone, an Android phone, or an iPad, and workers dial outbound only so no machine exposes an inbound port.

• Native rendering versus a cell-authoritative wire. cmux gets fidelity by being a GPU terminal in one process. Roost has to earn the same fidelity over a network, so the worker owns the authoritative cell grid: rebuilt at one agreed width on resize so the browser never re-reflows history, every frame stamped with a monotonic seq so a stale viewer gets exactly one authoritative full frame, scrollback fetched on demand, double-width CJK and emoji as one atomic two-column span, mouse tracking forwarded only when the running program asked for it, and predictive local echo above roughly 10 ms of round-trip time, suppressed inside alt-screen TUIs.

• A mobile companion versus the same app. cmux’s phone story is a companion paired to one Mac. Roost’s phone client is the desktop application: touch selection, an on-screen key row with a latching Ctrl, a swipeable deck of terminal cards, a soft keyboard that offsets content instead of reflowing the terminal, and PWA install.

• Agent state on the desk versus pushed to you. cmux’s notification rings fire on the Mac in front of you. Roost models working, needs input, and done on the sidebar row, the tab, the mobile card, and as a folder rollup, and delivers Web Push once a device grants permission, so a blocked agent finds you when you are not at the desk.

What you give up either way

• Choosing Roost costs you: GPU-native rendering, the embedded scriptable WebKit browser, the per-tab git branch, pull request, and listening-port annotations, and the feel of a native AppKit app. Roost has no in-app browser and no per-agent cost accounting.
• Choosing cmux costs you: Linux hosts, any client that is not that Mac or its TestFlight companion, a phone-native UI, voice dictation, and push that reaches you away from the machine.

Use cmux instead if…

You work on one Mac at your desk and want the most polished native terminal, GPU rendering, and an in-app scriptable browser. If your machine count is one and your client is always the keyboard in front of you, everything Roost spends on wire protocol, worker enrollment, and a browser client is overhead you will not get value from. The branch, pull request, and listening-port annotations on each tab are genuinely good triage affordances that Roost does not currently offer.

What cmux is

cmux is a native macOS terminal for running coding agents, built by Manaflow (YC S24) in Swift and AppKit on top of libghostty, so the grid is GPU-rendered by the same engine behind Ghostty. It is macOS only, organised around a vertical tab list where each session carries the context you need to triage parallel runs: the git branch, the pull request, and the ports that session is listening on. It is free under GPL-3.0, with a paid Founders Edition for early access.

• Also ships: notification rings driven by the OSC 9/99/777 escapes agents already emit, an embedded scriptable WebKit browser, a CLI plus a Unix-socket API for driving sessions from outside, session restore that brings back scrollback across reboots, SSH workspaces and remote-tmux attach in beta, and an iOS companion in TestFlight paired to one Mac.

Sources

• cmux (cmux.com)

Compare the rest of the field on the alternatives hub, or read how Roost’s wire protocol keeps a browser honest in terminal fidelity.