Codex CLI Install

First you need to make sure you meet these requirements:

Requirement	Details
Operating systems	macOS 12+, Ubuntu 20.04+/Debian 10+, or Windows 11 via WSL2
Node.js	22 or newer (LTS recommended)
Git (optional, recommended)	2.23+ for built-in PR helpers
RAM	4-GB minimum (8-GB recommended)

Never run sudo npm install -g; fix npm permissions instead.

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First all we do is run

npm install -g @openai/codex

You can run npm list --global to validate that it installed correctly. You should see it listed as an installed package:

/Users/naderbaradar/.nvm/versions/node/v22.16.0/lib
├── @google/gemini-cli@0.1.7
├── @openai/codex@0.1.2505172129
├── corepack@0.32.0
└── npm@10.9.2

Next, you need to set your OpenAI API key as an environment variable.

export OPENAI_API_KEY="your-api-key-here"

To find your API key, log into The OpenAPI Platform

Do not share your API key with others or expose it in the browser or other client-side code.

You can test to make sure your API key was set with this command:

echo $OPENAI_API_KEY

Then finally, simply issue this codex command

codex

And that’s it! You should see the interface and can begin prompting