# fx — AI Coding Tool Review & Pricing

> fx is a tiny, native coding agent CLI written in Zig that focuses on minimalism, performance, and embeddability. It acts as a shell-like coding harness that supports interactive sessions, automated tasks via subagents, and extensibility through MCP servers and custom skills.

Source: https://ai.dosa.dev/tools/fxsh · Updated Oct 15, 2026 · Category: Terminal & CLI Agents · Published by dosa.dev

## At a glance

- **Tool**: fx
- **Company**: Vercel
- **Category**: [Terminal & CLI Agents](https://ai.dosa.dev/category/cli-agents)
- **Pricing model**: Freemium
- **Official website**: https://fx.sh/

## Key features

- Native binary with small footprint (~6 MiB) and high performance
- Model-agnostic support for Vercel AI Gateway, Grok, Codex, and custom endpoints
- Support for MCP servers and custom skill definitions for extended capabilities
- Built-in permission system with auto-review modes for safety
- Embeddable core (libfx) for Node.js and WebAssembly environments

## Pricing

**Model**: Freemium

fx is open source, but model access requires subscriptions or API keys from providers like Vercel AI Gateway, OpenAI (Codex), or xAI (Grok). An optional 'Ultrafast' tier is available through AI Gateway at a higher price point.

## Who it is for

- **Best for**: Developers who need a high-performance, lightweight, and scriptable coding agent that integrates directly into terminal workflows and CI/CD pipelines.
- **Not ideal for**: Users who prefer a full GUI-based IDE experience or those who cannot provide their own API keys or subscription credentials for model inference.

## Verdict

fx is a powerful, exceptionally fast coding agent for terminal power users who value minimalism and low-latency interaction, though it requires users to bring their own model subscriptions or gateway credentials.

## Recent updates

Recent updates introduced the 'Ultrafast' inference tier for supported OpenAI models, active-turn steering via Ctrl+Enter, and major performance optimizations that significantly reduce launch, shell call, and session resume times. Additional improvements include simplified subagent interfaces, enhanced MCP management, and better context compaction.

## Frequently asked questions

### Is fx free?

fx is Freemium. fx is open source, but model access requires subscriptions or API keys from providers like Vercel AI Gateway, OpenAI (Codex), or xAI (Grok). An optional 'Ultrafast' tier is available through AI Gateway at a higher price point. Check the official site for current plans.

### Is fx open source?

fx is not listed as open source on ai.dosa.dev - it is Freemium.

### How much does fx cost?

fx is open source, but model access requires subscriptions or API keys from providers like Vercel AI Gateway, OpenAI (Codex), or xAI (Grok). An optional 'Ultrafast' tier is available through AI Gateway at a higher price point. Pricing changes often - verify on the official site.

### Who is fx best for?

Developers who need a high-performance, lightweight, and scriptable coding agent that integrates directly into terminal workflows and CI/CD pipelines.

### Who is fx not ideal for?

Users who prefer a full GUI-based IDE experience or those who cannot provide their own API keys or subscription credentials for model inference.

### What are the best fx alternatives?

The closest fx alternatives on ai.dosa.dev are Claude Code, Codex CLI, Amp - all listed under Terminal & CLI Agents.

### Who makes fx?

fx is developed by Vercel. It is listed in the Terminal & CLI Agents category on ai.dosa.dev.

## Top alternatives

- [Claude Code](https://ai.dosa.dev/tools/claude-code) (Freemium) — Solo founders, indie hackers, and developers working in real-world codebases who need help with complex, multi-file engineering tasks like refactoring and bug fixing.
- [Codex CLI](https://ai.dosa.dev/tools/codex-cli) (Freemium) — Developers needing a terminal-integrated agent for coding tasks, local repository refactoring, automated testing, and code reviews.
- [Amp](https://ai.dosa.dev/tools/amp) (Freemium) — Developers who need autonomous agents to handle long-running tasks, code reviews, testing, and complex multi-step feature implementation across different environments.
- [Aider](https://ai.dosa.dev/tools/aider) (Open Source) — Developers comfortable with command-line workflows who want full control over model selection, git-centric history, and cost-efficient coding without subscription markups.
- [Gemini CLI](https://ai.dosa.dev/tools/gemini-cli) (Freemium) — Developers who need AI-powered coding assistance, terminal-based automation, and direct control over their workflow within their local shell.
- [Goose](https://ai.dosa.dev/tools/goose) (Free) — Developers and teams who require a vendor-neutral, highly extensible agent platform that supports local execution and complex, multi-step workflow automation.
- Full alternatives guide: https://ai.dosa.dev/tools/fxsh/alternatives