⠀⠀⠀⠀⠀⠀⣠⣾⣿⣿⣿⠀⠀⠀⠀⠀⠀⠀⠀
 ⠀⠀⠀⠀⠀⢰⣿⡿⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
 ⠀⠀⠀⣠⣶⣿⣿⣷⣶⡶⣶⣶⣆⠀⠀⠀⣴⣶⣶⠆
 ⠀⠀⠀⠉⢹⣿⣿⠉⠉⠀⠘⢿⣿⣧⣀⣾⣿⡿⠃⠀             Tiny, open, embeddable, native coding agent.
 ⠀⠀⠀⠀⣼⣿⡏⠀⠀⠀⠀⠀⠻⣿⣿⣿⠟⠀⠀⠀
 ⠀⠀⠀⢀⣿⣿⠃⠀⠀⠀⠀⢠⣦⠘⢿⣿⣷⡀⠀⠀             curl -fsSL https://fx.sh/setup.sh | bash
 ⠀⠀⠀⣸⣿⡟⠀⠀⠀⠀⣰⣿⣿⠗⠀⠻⣿⣿⣄⠀
 ⠀⠀⠀⣿⣿⠇⠀⠀⠀⠾⠿⠿⠋⠀⠀⠀⠘⠿⠿⠦             ⚠ Status: Experimental. Use at your own risk.
  ⠀⣸⣿⡿⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
 ⣿⣿⣿⠟⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀

fx is a coding agent CLI written in Zig: a 6.17 MiB native binary that is open source (Apache-2.0), model-agnostic, and embeddable as a harness in larger systems. Its interface stays closer to a Unix shell than an IDE in the terminal.

Install

curl -fsSL https://fx.sh/setup.sh | bash

Get started

Sign in with one of:

• fx login: Vercel AI Gateway
• fx login codex: ChatGPT subscription (OpenAI Codex OAuth)
• fx login grok: Grok subscription (xAI OAuth)
• fx setup: AI Gateway API key

Then start the interactive shell from a project:

cd your_project
fx

Or make a one-shot request:

fx ask "explain the changes in this repository"

Inside the shell, run /help to browse interactive commands.

Embed fx

fx builds as a native binary or WebAssembly. Applications embedding fx can provide network transport, session storage, configuration, permission handling, and terminal I/O.

Surface	Use
fx acp	Connect the native agent to editors and other Agent Client Protocol clients.
createFxAgent()	Embed the agent core in a JavaScript host with fx-core.wasm.
createFxTerminal()	Embed the interactive terminal with fx-term.wasm.

The WebAssembly SDK is experimental. See the WebAssembly SDK and ACP documentation.

The SDK is published to npm as libfx. For runnable Node.js, browser, Next.js, and Nuxt applications, see the libfx examples.

Extend fx

• Skills: reusable instructions the agent loads when invoked
• MCP: connect external tools and servers
• Subagents: delegate independent work

Documentation

Read the fx documentation for sessions, models, permissions, configuration, and the full CLI and slash command references.

Build from source

Building fx requires Zig 0.16.0+:

git clone https://github.com/vercel-labs/fx.git
cd fx
zig build -Doptimize=ReleaseSafe
./zig-out/bin/fx

Run the test suite with zig build test. See CONTRIBUTING.md for development and contribution guidelines.

License

Apache-2.0

Third-party licenses and attributions are listed in THIRD_PARTY_NOTICES.md.

Credits

Interface sounds by cuelume.