Key takeaways
- 5,200+ GitHub stars and growing — native Swift/AppKit app built on libghostty for GPU-accelerated terminal rendering
- Notification rings and sidebar badges solve the 'which agent needs me?' problem across dozens of parallel sessions
- Agent-agnostic terminal — works with any CLI agent out of the box, no lock-in to specific workflows
FAQ
What is cmux?
cmux is a free, open-source native macOS terminal app built on libghostty that adds vertical tabs, notification rings, split panes, and a built-in browser — optimized for running parallel AI coding agents.
How much does cmux cost?
cmux is free and open source under the AGPL-3.0 license.
Who competes with cmux?
Ghostty (standalone terminal without agent features), Supacode (also libghostty-based), and Agentastic (native Swift with code review). For orchestration, Tembo.
Does cmux manage git worktrees?
No. cmux is a terminal, not an orchestrator. It shows git branch and PR status in the sidebar but doesn't create or manage worktrees — pair it with dmux or manual worktree workflows.
What's the relationship between cmux and Ghostty?
cmux uses libghostty as a library for terminal rendering, similar to how apps use WebKit. It reads your existing Ghostty config for themes, fonts, and colors. Ghostty is a standalone terminal; cmux adds agent-focused features on top.
Executive Summary
cmux is a native macOS terminal app built on libghostty that solves a specific pain point: knowing which of your many parallel coding agents needs attention.[1] It adds vertical tabs with notification rings, a sidebar showing git branch and PR status, split panes, and a built-in scriptable browser — all in a Swift/AppKit app that reads your existing Ghostty config.
| Attribute | Value |
|---|---|
| Company | Manaflow AI |
| Founded | 2026 |
| Funding | Unknown (Manaflow has a separate commercial product) |
| Headquarters | Unknown |
| GitHub Stars | ~5,200 |
Product Overview
cmux was born from the frustration of running many Claude Code and Codex sessions in Ghostty split panes, where native macOS notifications all say the same unhelpful "Claude is waiting for your input."[1] The creator wanted a terminal that could show which agent needs attention at a glance.
Unlike orchestrators that manage agent lifecycles, cmux is a terminal — it provides the environment where agents run, with better notification and organization primitives. Any CLI agent works out of the box.
Key Capabilities
| Capability | Description |
|---|---|
| Notification Rings | Blue ring around panes + sidebar badges when agents need attention |
| Vertical Tabs | Sidebar shows git branch, PR status, working directory, listening ports, latest notification |
| Split Panes | Horizontal and vertical splits within workspaces |
| Built-in Browser | Scriptable browser API (ported from Vercel's agent-browser) alongside terminal |
| Socket API | CLI and socket API for automation — create workspaces, split panes, send keystrokes |
| Ghostty Compatible | Reads existing ~/.config/ghostty/config for themes, fonts, colors |
| GPU Accelerated | Powered by libghostty for smooth rendering |
Product Surfaces
| Surface | Description | Availability |
|---|---|---|
| macOS App | Native Swift/AppKit desktop app | GA |
| CLI | cmux command for scripting and automation | GA |
Technical Architecture
cmux is a native Swift/AppKit application that embeds libghostty as a library for terminal rendering.[2] This is the same approach as using WebKit for web views — Ghostty provides the terminal engine, cmux adds the UI chrome and notification system.
Key Technical Details
| Aspect | Detail |
|---|---|
| Deployment | macOS app (.dmg or Homebrew) |
| Runtime | Native Swift/AppKit, GPU-accelerated via libghostty |
| Model(s) | None — agent-agnostic terminal |
| Integrations | Any CLI agent, Ghostty config, git, GitHub PRs |
| Open Source | Yes (AGPL-3.0) |
Strengths
- Notification system is the killer feature — Blue rings on panes, sidebar badges, notification popover, and native macOS notifications triggered via terminal escape sequences (OSC 9/99/777) or CLI hooks[1]
- Native performance — Swift/AppKit with libghostty means fast startup, low memory, and GPU-accelerated rendering — no Electron tax
- Zero lock-in — It's a terminal; any agent that runs in a terminal works. No opinionated workflow imposed[2]
- Scriptable — Socket API and CLI for creating workspaces, splitting panes, sending keystrokes, and controlling the built-in browser — enables custom orchestration
- Strong community signal — 5,200+ GitHub stars, Product Hunt launch, active Discord; clearly resonating with developers[3]
Cautions
- macOS only — No Windows, Linux, or web version; limits team adoption in mixed-OS environments
- Not an orchestrator — Doesn't manage git worktrees, agents, or tasks; you still need to set up and launch agents yourself
- AGPL-3.0 license — More restrictive than MIT; may deter some enterprise or commercial adopters
- Manaflow has a separate commercial product — The relationship between free cmux and commercial Manaflow (container-based agent orchestration) is unclear[4]
- No worktree management — Shows git branch in sidebar but doesn't create/manage worktrees; pair with dmux or similar for isolation
Pricing & Licensing
| Tier | Price | Includes |
|---|---|---|
| Open Source | Free | Full functionality |
Licensing model: AGPL-3.0 — free to use, source must be shared if distributed as a service.
Hidden costs: None for cmux itself. Agent CLI subscriptions are separate.
Competitive Positioning
Direct Competitors
| Competitor | Differentiation |
|---|---|
| Ghostty | cmux adds notifications, vertical tabs, sidebar, browser — Ghostty is the raw terminal engine |
| Supacode | Also libghostty-based but adds worktree management — cmux is more terminal, less orchestrator |
| Agentastic | Native Swift with code review — cmux focuses on terminal primitives, not review workflows |
| Tembo | Full orchestration platform — cmux is the terminal layer, not the orchestration layer |
When to Choose cmux Over Alternatives
- Choose cmux when: You want a fast native terminal with notification awareness for parallel agents
- Choose Emdash when: You want GUI-based worktree management and issue tracker integration
- Choose dmux when: You want tmux-based worktree orchestration (pairs well with cmux's notification approach)
Ideal Customer Profile
Best fit:
- Developers running many parallel agent sessions who need notification management
- Ghostty users wanting agent-optimized features on top of their existing config
- Terminal-first developers who dislike Electron-based tools
Poor fit:
- Teams needing centralized orchestration, signed commits, or enterprise governance
- Developers wanting an all-in-one orchestrator that manages worktrees and agent lifecycles
- Mixed-OS teams (Windows/Linux users)
Viability Assessment
| Factor | Assessment |
|---|---|
| Financial Health | Moderate — backed by Manaflow (commercial product exists) |
| Market Position | Niche — terminal layer for agent workflows |
| Innovation Pace | Rapid — daily commits, active development |
| Community/Ecosystem | Strong — 5.2K stars, Product Hunt, Discord |
| Long-term Outlook | Positive — clear niche, strong community, sustainable model |
cmux fills a specific gap: the terminal itself. While orchestrators manage what agents do, cmux manages where you see them. The Manaflow commercial product suggests a sustainable business model behind the open-source terminal.
Bottom Line
cmux is the best terminal app for developers running parallel coding agents on macOS. Its notification system — rings, badges, popover — solves the real problem of tracking which agent needs you across dozens of sessions. It deliberately stays out of orchestration, making it a composable building block rather than an opinionated platform.
Recommended for: macOS developers running parallel agent sessions who want native performance and notification awareness.
Not recommended for: Teams needing orchestration, worktree management, or cross-platform support.
Outlook: cmux will likely become the default terminal for Mac developers using AI coding agents. Its composable approach pairs well with orchestrators, and the Manaflow commercial backing provides sustainability. Watch for potential premium features or Manaflow integration.
Research by Ry Walker Research • methodology