Do the install

Follow the path that matches your machine. Either one ends with Codex installed.

Path A: Homebrew (Mac, if you have brew)

One command, in your terminal:

brew install --cask codex

It downloads and sets up Codex. When it finishes, skip ahead to the next step to verify it.

Path B: npm (any machine)

First, check whether you already have Node. Type:

node --version

If that prints a version number that's 18 or higher, you have Node. Skip straight to the install command at the bottom of this step.

If it says command not found, you need Node first. Get it the simple way:

• Go to nodejs.org in your browser.
• Download the version it offers you (the page detects your operating system). Take the one labeled "LTS", which means the stable one.
• Run the downloaded installer the way you'd install any app: open it, click through, accept the defaults.
• Close your terminal, open a fresh one, and run node --version again. You should see a version number now.

Installing Node is a normal app install with an installer window. It is not a terminal puzzle. Once node --version prints a number, install Codex:

npm i -g @openai/codex

It prints some lines as it works and finishes in well under a minute.

Whichever path you took, Codex is now installed. The next step confirms it, the same way you confirmed the Claude CLI: by asking it for its version.