Minimal native CLI
fx is a terminal-first coding agent with a shell-like interface, designed to keep output compact and focus on the current workspace.
fx
Freemium
fx is a tiny, open, native coding agent and CLI for working with code from the terminal. It is designed for research, embeddability, and use as part of larger systems, with support for local or cloud inference.
What is fx?
fx is a CLI-based coding agent written in Zig. It is designed to run from the terminal, work as a native process, and fit into larger systems through embedding or protocol-based integrations. The project emphasizes a small binary, minimal output, and a workflow that is closer to a Unix shell than a full terminal IDE.
The documentation describes fx as model-agnostic and open source under Apache-2.0. It can be used interactively in a project directory, resumed across sessions, or run noninteractively with fx ask. The same runtime can also be exposed over Agent Client Protocol or compiled to WebAssembly for JavaScript-based interfaces.
What can fx do?
Interactive and noninteractive modes
Users can start a fresh session with `fx`, continue an existing session with `fx resume`, or run a single request with `fx ask`.
Workspace-aware execution
The current directory becomes the primary workspace, and commands such as reading, searching, and listing files work within that context.
Permission-aware actions
fx starts in auto permission mode, reviews sensitive calls, and prompts before actions that can change files or run commands. Permission mode can be changed with `/permissions`.
Multiple deployment surfaces
The same agent can run natively in the terminal, serve over ACP with `fx acp`, or be loaded from JavaScript through the experimental WebAssembly SDK.
Extensible agent runtime
The docs mention skills, plugins, MCP, browser integration, and configurable SDK behavior for authentication, storage, command execution, and network requests.
Use Cases
“Terminal-based code assistance”
Work in a repository, ask fx to inspect files, explain code, add tests, or run the test suite while the transcript shows tool calls as they happen.
“Session-based development workflows”
Resume prior work, inspect saved sessions, and recover context when you return to a project later.
“Embedded coding-agent interfaces”
Use fx as the runtime behind an editor, application, or service that needs coding-agent behavior without building the agent from scratch.
“JavaScript or browser-hosted agent experiences”
Load the WebAssembly build into a JS application when you need a headless agent or an interactive terminal-like interface.
“Controlled automation with approvals”
Use fx in environments where file access and command execution should be reviewed before they run.
Frequently Asked Questions
What is fx?
fx is a CLI-based AI coding agent and harness for working with code from the terminal or embedding the agent into other systems.
How do I start using it?
The docs show installation with `curl -fsSL https://fx.sh/setup.sh | bash`, followed by `fx login` for Vercel authentication or setup of an AI Gateway API key.
Can fx run without an interactive terminal session?
Yes. The docs document `fx ask` for one-off requests, along with commands such as `fx status`, `fx models`, and `fx permissions` for inspection and configuration.
Does fx only work with one model provider?
No. The site describes fx as model-agnostic and suitable for local models, gateways, direct provider API access, or subscriptions.
Can fx be embedded in other products?
Yes. The docs describe native ACP support and an experimental WebAssembly SDK for JavaScript-based integrations.
Quick Facts
- Category
- Developer Tool
- Platform
- CLI, native process, ACP, WebAssembly
- Primary users
- Developers working in repositories or teams embedding a coding agent
- License
- Apache-2.0
- Source domain
- fx.sh
- Status
- Experimental
fx Traffic Analysis
Traffic data is for reference only.
- Domain Rating
- 69
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