How to Install CodeX: Complete Guide for Windows, Linux, and MacOS

CodeX is OpenAI's cutting-edge AI coding CLI tool powered by the latest GPT-5 model. If you're looking to supercharge your development workflow with AI-assisted coding, this guide walks you through the complete installation process across all major operating systems.

Whether you're on Windows, Linux, or MacOS, getting CodeX up and running is straightforward once you know the steps. Let's dive into the installation process for each platform.

Installing CodeX on Windows

Getting Your CodeX Account Ready

First things first—you'll need an account to use CodeX. The setup involves creating your account and obtaining an API key that connects your local installation to the service.

Once you have your account, head to the API Keys section of your dashboard to generate a new key. Keep this handy—you'll need it in just a moment.

Installing the Official Package

Before installing CodeX, make sure your Node.js version is 18 or higher. You can check this by running node -v in your terminal.

If you're good to go, install CodeX globally using npm:

npm install -g @openai/codex

The installation should complete within a few minutes depending on your internet connection.

Configuring CodeX for First Use

Navigate to C:\users\your-username and create a .codex folder. If this folder already exists, delete it first to ensure a clean setup.

Inside the .codex folder, create a file named auth.json with the following content:

{"OPENAI_API_KEY":"your_api_key_here"}

Next, create a config.toml file in the same directory. If one already exists, delete it first. For developers working with AI coding tools, having a properly configured setup ensures smooth integration with your existing workflow. 👉 Check out AICodeMirror for seamless API access and enhanced coding capabilities

Paste this configuration into your config.toml file:

model_provider = "aicodemirror"
model = "gpt-5-codex"
model_reasoning_effort = "high"
disable_response_storage = true
preferred_auth_method = "apikey"

[model_providers.aicodemirror]
name = "aicodemirror"
base_url = "https://api.aicodemirror.com/api/codex/backend-api/codex"
wire_api = "responses"

After saving both files, restart your terminal and verify the installation:

codex -V

You should see the version number displayed, confirming everything is set up correctly.

Starting Your First CodeX Session

Navigate to any project folder where you want to use CodeX:

cd your-project-folder
codex

When you first launch CodeX on Windows, it may suggest using WSL (Windows Subsystem for Linux). You can safely skip this prompt if you prefer working directly in Windows.

Pro tip: Use codex --dangerously-bypass-approvals-and-sandbox to skip frequent authorization prompts during development. CodeX also integrates seamlessly with the official VSCode extension for an even smoother coding experience.

Installing CodeX on Linux

Account Setup and Package Installation

The Linux installation follows a similar pattern to Windows, starting with your account setup and API key generation from the dashboard.

Install CodeX using npm (Node.js 18+ required):

npm install -g @openai/codex

Linux-Specific Configuration

Create the configuration directory in your home folder:

rm -rf ~/.codex
mkdir ~/.codex

Create auth.json in ~/.codex:

{"OPENAI_API_KEY":"your_api_key_here"}

Then create config.toml with the same configuration content shown in the Windows section above. The configuration remains identical across platforms, making it easy to maintain consistent setups across different development environments.

Verify the installation:

codex -V

Running CodeX on Linux

Launch CodeX in any project directory:

cd your-project-folder
codex

The --dangerously-bypass-approvals-and-sandbox flag works the same way on Linux if you want to streamline your workflow.

Installing CodeX on MacOS

Setting Up on Mac

The MacOS installation process mirrors the Linux approach. After setting up your account and generating your API key, install the package:

npm install -g @openai/codex

MacOS Configuration Steps

Create your configuration directory:

rm -rf ~/.codex
mkdir ~/.codex

Add your auth.json file in ~/.codex:

{"OPENAI_API_KEY":"your_api_key_here"}

Create the config.toml file with the same configuration used for Windows and Linux. When building modern AI-powered development tools, having reliable API infrastructure makes all the difference. 👉 Explore AICodeMirror's robust API platform for your coding projects

Confirm everything works:

codex -V

Launching CodeX on Mac

Start using CodeX in your projects:

cd your-project-folder
codex

Final Thoughts

CodeX brings powerful AI coding assistance to your terminal, regardless of your operating system. The installation process is remarkably consistent across platforms—the main differences lie in file path conventions rather than actual functionality.

Once installed, CodeX becomes an indispensable part of your development toolkit. Whether you're debugging complex issues, generating boilerplate code, or exploring new frameworks, having GPT-5 powered assistance at your fingertips accelerates your workflow significantly.

Remember to keep your API keys secure and never commit them to version control. Happy coding!