> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/openai/codex/llms.txt
> Use this file to discover all available pages before exploring further.

# Introduction to Codex CLI

> A local coding agent from OpenAI that runs directly in your terminal

# Introduction to Codex CLI

Codex CLI is a coding agent from OpenAI that runs locally on your computer. It brings ChatGPT-level reasoning with the power to execute code, manipulate files, and iterate — all under version control.

## What is Codex CLI?

Codex CLI is built for developers who live in the terminal and want ChatGPT-level reasoning with the ability to execute code, manipulate files, and iterate. It's chat-driven development that understands and executes your repo.

<CardGroup cols={2}>
  <Card title="Get started" icon="rocket" href="/installation">
    Install Codex CLI and get up and running in minutes
  </Card>

  <Card title="Authentication" icon="key" href="/authentication">
    Sign in with ChatGPT or configure API key authentication
  </Card>

  <Card title="Quickstart guide" icon="bolt" href="/quickstart">
    Run your first commands and see Codex in action
  </Card>

  <Card title="Core concepts" icon="book" href="/core-concepts">
    Learn about approval modes, sandboxing, and more
  </Card>
</CardGroup>

## Why use Codex CLI?

Codex CLI is designed for developers who already work in the terminal and want powerful AI assistance without leaving their workflow.

### Key features

**Zero setup**

Bring your OpenAI API key or sign in with ChatGPT and it just works. No complex configuration required.

**Safe and secure**

Codex runs in a sandbox with network disabled and directory restrictions. Full auto-approval is safe because commands are isolated from your system.

**Full auto-approval**

Let Codex work autonomously while staying secure. In full auto mode, commands run network-disabled and directory-sandboxed.

**Multimodal**

Pass in screenshots or diagrams to implement features. Codex understands visual context.

**Open source**

Fully open source so you can see how it works and contribute to development.

## How it works

Codex CLI operates in three approval modes, giving you control over how much autonomy the agent has:

* **Suggest** (default): Codex reads files and suggests changes. You approve all file writes and shell commands.
* **Auto Edit**: Codex reads and writes files automatically. You approve shell commands.
* **Full Auto**: Codex reads, writes files, and executes commands. All operations run in a sandbox with network disabled.

<Note>
  In full auto mode, every command runs network-disabled and confined to your working directory for defense-in-depth. Codex will warn you if you start in auto modes without Git tracking.
</Note>

## Example use cases

<CodeGroup>
  ```bash Refactor code theme={null}
  codex "Refactor the Dashboard component to React Hooks"
  ```

  ```bash Generate migrations theme={null}
  codex "Generate SQL migrations for adding a users table"
  ```

  ```bash Write tests theme={null}
  codex "Write unit tests for utils/date.ts"
  ```

  ```bash Create an app theme={null}
  codex --approval-mode full-auto "create a fancy todo-list app"
  ```
</CodeGroup>

Codex rewrites code, runs tests, generates files, and iterates until the task is complete.

## Next steps

<Steps>
  <Step title="Install Codex CLI">
    Follow the [installation guide](/installation) to get Codex running on your system.
  </Step>

  <Step title="Authenticate">
    Sign in with ChatGPT or configure your API key using the [authentication guide](/authentication).
  </Step>

  <Step title="Run your first command">
    Complete the [quickstart](/quickstart) to see Codex in action.
  </Step>
</Steps>