How to Install OpenAI Codex CLI on Windows 11

OpenAI Codex CLI is a coding agent that runs directly in your terminal. It reads your project files, edits code, and executes commands without leaving your command line. If you spend a lot of time switching between a browser, an editor, and a terminal, Codex CLI keeps that workflow in one place.

This guide walks you through installing Codex CLI on Windows 11, signing in, and running your first session.

What You Need Before You Start

Before you install Codex CLI, check these two requirements:

• A supported ChatGPT plan: Codex CLI requires a ChatGPT Plus, Pro, Business, Edu, or Enterprise subscription. If you use the free tier, you will need to upgrade or use an OpenAI API key instead.
• Node.js installed on your PC: The installer uses npm, which comes bundled with Node.js. If you do not have Node.js, download the LTS version from nodejs.org and install it. Open a terminal after installation and run node -v to confirm it works.

How to Install OpenAI Codex CLI on Windows 11

Codex CLI installs as a global npm package. Open PowerShell or Windows Terminal and run:

npm i -g @openai/codex

npm downloads and installs the package globally. The process takes under a minute on most connections.

To confirm the installation worked, run:

codex --version

Windows 11 supports Codex CLI natively in PowerShell. If you need a Linux-native environment for your project, use WSL2 instead and run the same install command inside your WSL terminal.

How to Sign In and Run Codex CLI

Once installed, start Codex CLI by running:

codex

The first time you run this command, Codex prompts you to authenticate. You have two options:

• Sign in with your ChatGPT account if you have an active Plus, Pro, Business, Edu, or Enterprise plan.
• Enter an OpenAI API key if you prefer to connect via the API directly.

After you authenticate, Codex opens an interactive terminal UI (TUI). From here, you type prompts and Codex reads your project files, suggests changes, and runs commands based on what you ask.

What Can You Do with OpenAI Codex CLI

• Switch models: Type /model inside a session to switch between GPT-5.4, GPT-5.3-Codex, and other available models. You can also adjust the reasoning level from the same menu.
• Attach images: You can upload screenshots or design specs alongside your prompt. Codex reads the image and uses it as context when generating or editing code.
• Run a code review: Ask Codex to review your code before you commit. A separate Codex agent checks your changes and flags issues.
• Search the web: Codex can search the web to pull in current information during a task, which is useful when you need documentation or package details.
• Use MCP tools: Codex supports Model Context Protocol (MCP), which connects it to third-party tools and external context sources.
• Control approval mode: Before Codex edits files or runs commands, you can set an approval mode that decides how much it does automatically versus what it asks you to confirm first.

How to Upgrade Codex CLI

OpenAI releases new versions of Codex CLI regularly. To upgrade to the latest version, run:

npm i -g @openai/codex@latest

Run this command periodically to stay on the most recent build. Check the Codex CLI changelog on GitHub for details on what each release changes.

If you run into issues after installation, confirm that your Node.js version is current and that your ChatGPT plan includes Codex access. Both are the most common reasons the setup does not work on the first try.

FAQs